Free ASCP MLS Exam Practice Questions Mock Test: Part 42 – Peripheral Blood Smear and Morphology

• Stomatocytes are red blood cells with a central slit or “mouth-shaped” area of pallor on a peripheral blood smear.

• They are associated with:

  • Alcoholism

  • Hereditary stomatocytosis (a rare genetic disorder)

  • Liver disease (particularly obstructive liver disease)

  • Some acquired hemolytic anemias

The other options are incorrect:

• b) Iron deficiency anemia → Shows microcytic, hypochromic cells, not stomatocytes.

• c) G6PD deficiency → Shows bite cells and Heinz bodies during hemolytic crises.

• d) Aplastic anemia → Generally shows normocytic cells without specific stomatocytosis.

The description of “blue, ring-shaped inclusions with red chromatin dots” is the classic appearance of early ring trophozoites of Plasmodium falciparum (and other Plasmodium species) inside red blood cells.

• The blue cytoplasm forms the ring shape.

• The red chromatin dot is the parasite’s nuclear material.

The other options are incorrect:

• b) Howell-Jolly bodies → Appear as solid, round, dark purple nuclear remnants. They are not ring-shaped and do not have a separate red chromatin dot.

• c) Cabot rings → Appear as thin, ring-shaped or figure-eight-shaped, reddish-purple structures. They are not described as having a blue ring with a distinct red dot.

• d) Basophilic stippling → Appears as multiple, diffuse, fine blue granules dispersed throughout the red cell. It does not form a ring structure with a red chromatin dot.

• A hypersegmented neutrophil is defined as having six or more nuclear lobes.

• This is a classic morphological finding associated with megaloblastic anemia (due to vitamin B12 or folate deficiency), where impaired DNA synthesis leads to abnormal nuclear maturation.

The other options are incorrect:

• b) A Pelger-Huët cell → This is a hyposegmented neutrophil, typically with a bilobed (“dumbbell” or “pince-nez”) nucleus.

• c) A smudge cell → This is a ruptured lymphocyte, commonly seen in chronic lymphocytic leukemia (CLL).

• d) A reactive cell → This is a nonspecific term and not used to describe neutrophil hypersegmentation.

• Macro-ovalocytes are large, oval-shaped red blood cells.

• They are the most characteristic red cell finding in megaloblastic anemias (caused by vitamin B12 or folate deficiency), where impaired DNA synthesis leads to abnormal, enlarged erythroid precursors.

The other options are associated with different red cell morphologies:

• a) Sickle cell anemia → Sickled cells

• c) Thalassemia → Microcytosis, target cells

• d) Sideroblastic anemia → Dimorphic picture (microcytic and normocytic cells), Pappenheimer bodies

• Under normal conditions in a peripheral blood smear, the monocyte is typically the largest white blood cell, with a diameter ranging from 12 to 20 micrometers.

• It has a large, kidney-shaped or folded nucleus and abundant, grayish-blue cytoplasm that may contain fine granules or vacuoles.

The other white blood cells are generally smaller:

• a) Neutrophil: 10–15 micrometers

• b) Lymphocyte: 7–15 micrometers (small lymphocytes are much smaller)

• d) Eosinophil: 12–17 micrometers

• Pappenheimer bodies are small, basophilic iron-containing granules usually found at the periphery of the red blood cell.

• They are composed of ferritin aggregates (non-heme iron) and are confirmed with a Prussian blue stain, which turns the iron blue.

The other options are incorrect:

• a) Cabot rings → Thought to be remnants of the mitotic spindle; do not contain iron and do not stain with Prussian blue.

• b) Heinz bodies → Composed of denatured hemoglobin; require a supravital stain like crystal violet, not Prussian blue.

• d) Howell-Jolly bodies → Composed of residual nuclear DNA; do not contain iron.

• The term “shift to the left” in hematology refers to the presence of increased immature granulocyte precursors (such as bands, metamyelocytes, and myelocytes) in the peripheral blood.

• This typically indicates a heightened demand for neutrophils, most commonly due to a bacterial infection or an inflammatory state, which causes the bone marrow to release immature cells into the circulation.

The other options are incorrect:

• a) A calibration adjustment on an instrument → This is a technical term, not the hematological meaning.

• c) A trend on a Levy-Jennings chart → Refers to quality control in laboratory testing, not blood cell morphology.

• d) A microscope adjustment → This is a literal, physical adjustment, not the clinical term.

• Toxic granulation appears as prominent, dark blue-purple granules in the cytoplasm of neutrophils.

• It is a sign of accelerated granulopoiesis and is commonly seen in severe bacterial infections, as well as other conditions involving inflammation, sepsis, or toxic states.

The other options are incorrect:

• a) Viral infections → Typically cause lymphocytosis, not toxic granulation.

• c) Megaloblastic anemia → Causes hypersegmented neutrophils, not toxic granulation.

• d) Thalassemia → Affects red blood cell morphology, not neutrophil granulation.

• Acanthocytes (or spur cells) are red blood cells with a few irregular, large, finger-like projections with bulbous ends.

• They are associated with:

  1. Severe liver disease (especially alcoholic cirrhosis): Due to an imbalance of lipids in the RBC membrane.

  2. Abetalipoproteinemia: A genetic disorder affecting lipid absorption and transport.

  3. McLeod syndrome and other neuroacanthocytosis syndromes.

The other options are incorrect:

• b) Renal disease → Associated with echinocytes (burr cells), not acanthocytes.

• c) Megaloblastic anemia → Shows macro-ovalocytes and hypersegmented neutrophils.

• d) Lead poisoning → Shows basophilic stippling.

• Auer rods are needle-shaped, reddish-purple cytoplasmic inclusions found in myeloid lineage cells.

• They are composed of fused primary (azurophilic) granules and are pathognomonic for acute myeloid leukemia (AML).

• They are not found in lymphoblasts, megakaryocytes, or plasma cells. Their presence helps distinguish AML from acute lymphoblastic leukemia (ALL).

The other options are incorrect:

• a) Lymphoblasts → Do not contain Auer rods.

• c) Megakaryocytes → Do not contain Auer rods.

• d) Plasma cells → Do not contain Auer rods.

• Nucleated red blood cells (NRBCs or normoblasts) are immature red blood cells that normally reside in the bone marrow and are not present in the peripheral blood of healthy adults.

• Their appearance in the peripheral smear indicates bone marrow stress or infiltration, forcing early release of precursors. Common causes include:

  • Severe hemolytic anemia (increased erythropoietic demand)

  • Bone marrow infiltration (e.g., leukemia, metastasis, myelofibrosis)

  • Hypoxia or severe bleeding

  • Extramedullary hematopoiesis

The other options are incorrect or incomplete:

• b) Vitamin B12 deficiency → Causes megaloblastic anemia with macro-ovalocytes and hypersegmented neutrophils, but not typically NRBCs.

• c) Iron deficiency anemia → Shows microcytic, hypochromic cells, but NRBCs are not a characteristic feature.

• d) Aplastic anemia → Involves bone marrow failure; NRBCs are generally absent due to hypocellularity.

• Giant platelets (approaching the size of red blood cells or larger) are a hallmark finding in Bernard–Soulier syndrome.

• This is a rare inherited platelet disorder caused by a defect in the glycoprotein Ib-IX-V complex, leading to impaired platelet adhesion and the presence of these characteristically large platelets.

The other options are less characteristic:

• b) Aplastic anemia → Typically shows thrombocytopenia with normal or decreased platelet size, not giant platelets.

• c) Polycythemia vera → May have large platelets, but this is not the defining feature; giant platelets are most characteristic of Bernard–Soulier.

• d) Iron deficiency anemia → Usually shows normal to small platelets; in some severe cases, platelets may be large, but this is not the classic association.

• Ring forms (or signet ring forms) are a classic finding in malaria infection.

• They are the early trophozoite stage of the Plasmodium parasite, which appears as a ring-like structure inside the red blood cell on a peripheral blood smear.

The other options are incorrect:

• b) EBV → Causes atypical lymphocytes, not ring forms in RBCs.

• c) HIV → Can cause various hematological abnormalities but not ring forms in RBCs.

• d) CMV → Causes atypical lymphocytes, not ring forms in RBCs.

• Atypical lymphocytes (also called reactive lymphocytes) are enlarged, antigen-stimulated lymphocytes with abundant cytoplasm, often indented by surrounding red blood cells.

• They are most characteristically associated with infectious mononucleosis caused by the Epstein-Barr virus (EBV).

• They can also be seen in other viral infections (such as CMV, hepatitis), as well as in some bacterial infections and drug reactions.

The other options are incorrect:

• b) Bacterial sepsis → Typically shows neutrophilia with toxic granulation, not atypical lymphocytes.

• c) Leukemia only → Incorrect, as atypical lymphocytes are reactive/benign in most cases; leukemia shows malignant blast cells.

• d) Iron deficiency anemia → Affects red blood cells, not lymphocyte morphology.

• Döhle bodies appear as light blue, crescent-shaped cytoplasmic inclusions in neutrophils on a Wright-stained smear.

• They are composed of aggregated rough endoplasmic reticulum (ribosomes) and are a sign of accelerated granulopoiesis and toxic change in neutrophils.

• They are commonly seen in severe infections, burns, trauma, and other inflammatory conditions.

The other options are incorrect:

• a) Denatured hemoglobin → This describes Heinz bodies, found in red blood cells.

• c) Precipitated DNA → This describes Howell-Jolly bodies, found in red blood cells.

• d) Iron particles → This describes Pappenheimer bodies, found in red blood cells.

• Rouleaux formation occurs when red blood cells stack together like coins due to reduced electrostatic repulsion between them.

• This is most commonly caused by elevated levels of acute-phase proteins in the plasma, particularly fibrinogen and immunoglobulins.

• These same proteins also cause red blood cells to settle faster, leading to an increased erythrocyte sedimentation rate (ESR). Therefore, excessive rouleaux is a microscopic clue to an elevated ESR.

The other options are incorrect:

• a) Reticulocyte count → This indicates bone marrow response to anemia or blood loss; it is not directly related to rouleaux.

• c) Hematocrit & d) Erythrocyte count → These are measures of red cell mass and are not directly increased by the factors causing rouleaux. In fact, rouleaux is often seen in conditions like multiple myeloma, which may be associated with anemia.

• RDW (Red Cell Distribution Width) is a measure of the variation in red blood cell volume, reflecting anisocytosis.

• It is calculated from the red blood cell histogram and is typically reported as a coefficient of variation or standard deviation.

• A high RDW indicates a significant variation in red cell sizes, which can be seen in mixed deficiencies (e.g., iron and B12 deficiency) or early nutritional deficiencies.

The other options are incorrect:

• a) Hemoglobin concentration → This is measured by the MCHC (mean corpuscular hemoglobin concentration).

• c) Red cell shape variation (poikilocytosis) → This is assessed morphologically on a blood smear, not by the RDW.

• d) Mean red cell volume → This is the MCV (mean corpuscular volume).

• • In infectious mononucleosis (IM) caused by the Epstein–Barr virus (EBV), the virus infects B lymphocytes.

  • However, the large, reactive (atypical) lymphocytes seen on the peripheral blood smear are actually activated CD8⁺ T lymphocytes.

  • These reactive T cells proliferate in response to the EBV-infected B cells and appear as large cells with:

    • Abundant basophilic cytoplasm

    • Irregular (“ballerina skirt”) borders

    • Eccentric nucleus with coarse chromatin

• Bite cells (also called degmacytes) are red blood cells that appear to have one or more semicircular “bites” taken out of them.

• They form when the spleen removes Heinz bodies (denatured hemoglobin) from the red cell membrane, resulting in the “bitten” appearance.

• They are most characteristically seen in G6PD deficiency during an acute hemolytic episode, often triggered by oxidative stress (e.g., certain drugs, infections).

The other options are incorrect:

• a) Iron deficiency anemia → Shows microcytic, hypochromic cells, not bite cells.

• c) Aplastic anemia → Generally shows normocytic cells without specific poikilocytosis like bite cells.

• d) Pernicious anemia → A type of megaloblastic anemia showing macro-ovalocytes, not bite cells.

• Nucleated red blood cells (NRBCs) are immature RBCs released from the bone marrow.

• Polychromasia describes RBCs that stain bluish-gray due to the presence of residual RNA, indicating young RBCs (reticulocytes).

• Together, these findings indicate that the bone marrow is actively producing and releasing red blood cells prematurely, which is a sign of compensatory erythropoiesis.

Other options:

• a) Hemolytic anemia: May cause this finding, but the direct evidence on the smear represents regeneration, not the anemia itself.

• c) Megaloblastic anemia: Shows macro-ovalocytes and hypersegmented neutrophils, not NRBCs and polychromasia.

• d) Iron deficiency: Usually shows microcytosis and hypochromia, not regenerative features.

• Basophilic stippling appears as numerous, fine to coarse, blue-purple granules scattered evenly throughout the red blood cell on a Wright-stained smear.

• These granules represent aggregated ribosomes and mitochondrial remnants.

• It is associated with conditions such as lead poisoning, thalassemia, and other dyserythropoietic states.

The other options are incorrect:

• a) Large, blue cytoplasmic inclusions → This may describe Howell-Jolly bodies or other inclusions.

• b) Small, red granules throughout the RBC → This is not characteristic of basophilic stippling; red granules may refer to Pappenheimer bodies (which are iron-containing) but they appear blue on Wright stain and are often clustered.

• d) Ring-like structures on the RBC membrane → This describes malarial ring forms or possibly Cabot rings, not basophilic stippling.

• Microcytosis means the red blood cells (RBCs) are smaller than normal.

• This is a classic feature of iron deficiency anemia, because iron is necessary for adequate hemoglobin production; reduced hemoglobin leads to smaller RBCs.

The other options are typically associated with different RBC sizes:

• b) Megaloblastic anemia → Macrocytosis (larger RBCs)

• c) Aplastic anemia → Normocytic RBCs (usually normal size)

• d) Hemolytic anemia → Usually normocytic, though some chronic forms can cause microcytosis (but it is not the typical finding)

• A mature basophil is characterized by:

  • A bilobed nucleus that is often obscured by abundant granules.

  • Large, coarse, blue-black or purple-black granules that are water-soluble and may sometimes appear vacuolated if partially dissolved during staining.

The other options describe different cells:

• b) A segmented nucleus with large, orange-red granules → This describes an eosinophil.

• c) A round nucleus with no visible granules → This describes a lymphocyte.

• d) A horseshoe-shaped nucleus with fine pink granules → This describes a band neutrophil or metamyelocyte, not a basophil.

• Cabot rings are thin, ring-shaped or figure-eight-shaped, reddish-purple inclusions in red blood cells.

• They are thought to be remnants of the mitotic spindle or from abnormal microtubule assembly during cell division.

• They are most commonly associated with megaloblastic anemias (such as pernicious anemia due to B12 deficiency) and other severe dysplastic anemias affecting the bone marrow.

The other options are incorrect:

• b) Lead poisoning → Associated with basophilic stippling, not Cabot rings.

• c) Malaria → Shows malarial parasites inside RBCs, not Cabot rings.

• d) Sickle cell disease → Shows sickle cells, not Cabot rings.

• Schistocytes are fragmented red blood cells that appear as helmet cells, triangles, or other irregular shapes.

• They are indicative of microangiopathic hemolytic anemia, where red cells are physically sheared by fibrin strands in the small blood vessels.

• This is most commonly seen in:

  • Hemolytic Uremic Syndrome (HUS)

  • Disseminated Intravascular Coagulation (DIC)

  • Other causes include mechanical heart valves, malignant hypertension, and thrombotic thrombocytopenic purpura (TTP).

The other options are incorrect because:

• b) Iron deficiency anemia → Shows microcytic, hypochromic cells, not fragmentation.

• c) Aplastic anemia → Generally shows normocytic, normochromic cells without schistocytes.

• d) Megaloblastic anemia → Shows macro-ovalocytes, not schistocytes.

On a Sysmex DIFF scattergram:

• Side scatter (SSC) correlates with a cell’s internal granularity and structural complexity.

• Side fluorescence (SFL) correlates with nucleic acid content (DNA/RNA).

Neutrophils have these characteristics:

• High side scatter: Due to their abundant cytoplasmic granules and lobulated nucleus.

• Low side fluorescence: Because they are mature cells with a condensed, segmented nucleus (less DNA staining) and low RNA content.

The standard formula for a manual platelet estimate from a peripheral blood smear is:

Platelet count/μL ≈ Average number of platelets per oil immersion field (100x) × 20,000

This multiplier (20,000) is derived from the relationship between the average number of red blood cells and platelets in a microscopic field and the typical red blood cell count. Since a normal smear has about 8–10 platelets per field, this correlates with a normal platelet count of 150,000–400,000/μL.

Other options:

• a) 1,000, b) 10,000, c) 15,000 → Incorrect multipliers; they underestimate the platelet count.

• Hairy cell leukemia is a type of chronic lymphoproliferative disorder.

• The pathognomonic finding is the presence of abnormal B-lymphocytes with characteristic “hairy” cytoplasmic projections visible on a peripheral blood smear.

• These cells also typically have a round or indented nucleus and a loose chromatin pattern.

The other options are incorrect:

• b) Cells with large nucleoli only → This is not specific to hairy cell leukemia and can be seen in other leukemias.

• c) Lymphocytes with smudge appearance → This is characteristic of CLL, not hairy cell leukemia.

• d) Neutrophils with toxic granules → This is seen in severe bacterial infections, not hairy cell leukemia.

On a Siemens Advia hematology analyzer using the Perox channel (myeloperoxidase reaction):

• The scatterplot has an x-axis for peroxidase activity and a y-axis for volume (forward scatter).

• The numbered regions typically correspond to:

  • Region 2: Lymphocytes (low peroxidase, small size)

  • Region 3: Monocytes (moderate peroxidase, larger size)

  • Region 4 & 5: Neutrophils (high peroxidase)

  • Region 6: Eosinophils (very high peroxidase activity due to their abundant peroxidase-positive granules)

  • Region 1: Large unstained cells (LUCs)

• Schistocytes are fragmented red blood cells that appear as helmet cells, triangles, or other irregular shapes.

• They are indicative of microangiopathic hemolytic anemia (MAHA), a condition where red blood cells are physically sheared by fibrin strands in the small blood vessels.

• Common causes include:

  • Disseminated intravascular coagulation (DIC)

  • Thrombotic thrombocytopenic purpura (TTP)

  • Hemolytic uremic syndrome (HUS)

  • Mechanical heart valves or vascular grafts

The other options are incorrect:

• a) Liver disease → Typically causes target cells and acanthocytes, not schistocytes.

• b) Megaloblastic anemia → Shows macro-ovalocytes and hypersegmented neutrophils.

• d) Hemoglobinopathy → Shows sickle cells (in sickle cell anemia) or target cells (in thalassemia).

• EDTA (Ethylenediaminetetraacetic acid) is the anticoagulant of choice for hematology testing, including preparing peripheral blood smears for manual differential counts.

• It preserves cellular morphology best by chelating calcium, which prevents clotting without significantly distorting the appearance of white blood cells, red blood cells, or platelets.

The other anticoagulants are less suitable:

• a) Heparin → Can cause background staining interference (bluish tint) and may not preserve cell morphology as well as EDTA.

• b) Sodium citrate → Used primarily for coagulation studies; its liquid form can dilute the sample, affecting cell ratios.

• c) Potassium oxalate → Can cause cell shrinkage and distortion, making it unsuitable for morphological evaluation.

• Cabot rings are thin, ring-shaped or figure-eight-shaped, reddish-purple inclusions found in red blood cells.

• They are believed to be remnants of the mitotic spindle (microtubules) from a previous cell division stage.

• They are most commonly seen in megaloblastic anemias (e.g., vitamin B12 or folate deficiency) and other severe dysplastic anemias.

The other options are incorrect:

• a) Nuclear material → This describes Howell-Jolly bodies.

• b) Mitochondria → Not associated with Cabot rings.

• d) Denatured hemoglobin → This describes Heinz bodies.

• Plasma cells are characterized by:

  • Eccentric nucleus (off to one side)

  • Deep blue cytoplasm (due to abundant RNA)

  • Prominent perinuclear hof (a clear area near the nucleus representing the Golgi apparatus)

The other options are incorrect:

• a) Reactive lymphocyte → Has a larger, often irregular nucleus with a lighter blue cytoplasm, and may have a visible Golgi zone, but not typically as prominent as in plasma cells.

• c) Monocyte → Has a kidney-shaped or folded nucleus and a grayish-blue, granular cytoplasm, without a prominent perinuclear hof.

• d) Myelocyte → A precursor cell in the granulocytic lineage with a round nucleus and primary/secondary granules; no prominent perinuclear hof.

The description of a round, pyknotic (dense, condensed) nucleus and abundant, pinkish-gray cytoplasm is characteristic of an orthochromatic normoblast (also called a metarubricyte).

• This is the final, mature stage of nucleated red blood cell development in the bone marrow before the nucleus is extruded to form a reticulocyte.

• The cytoplasm appears pinkish-gray due to a high concentration of hemoglobin.

• The nucleus is small, dark, and pyknotic, ready to be expelled.

The other options are incorrect:

• a) Basophilic normoblast → Has a deeply basophilic (blue) cytoplasm and a larger nucleus with nucleoli.

• b) Polychromatophilic normoblast → Has a grayish-blue cytoplasm (mix of hemoglobin and RNA) and a more condensed but not yet pyknotic nucleus.

• d) Pronormoblast → The earliest stage; has a large nucleus with nucleoli and intensely basophilic cytoplasm.

• Reactive lymphocytes (also called atypical lymphocytes) are antigen-stimulated lymphocytes, typically T cells, that appear in response to viral infections (like infectious mononucleosis).

• Their characteristic features include:

  • Large size (can be as large as monocytes or larger)

  • Irregular or indented nucleus

  • Abundant, deeply basophilic (blue) cytoplasm

The other options are incorrect:

• a) Small size, clumped chromatin, scanty cytoplasm → This describes a normal, resting mature lymphocyte.

• c) Large size, round nucleus, granular cytoplasm → This is more characteristic of a monocyte or a different cell type.

• d) Small size, nucleoli, pale blue cytoplasm → This describes a lymphoblast, not a reactive lymphocyte.

• Echinocytes (also called burr cells) are red blood cells with evenly spaced, short, blunt spicules around their surface.

• They are often artifactual due to slow drying of the blood smear or elevated pH.

• However, their consistent presence can be associated with specific conditions, most notably uremia (kidney failure). They can also be seen in pyruvate kinase deficiency and following blood storage.

The other options are incorrect:

• b) Iron deficiency anemia → Shows microcytic, hypochromic cells, not echinocytes.

• c) G6PD deficiency → Shows bite cells and Heinz bodies during hemolytic crises.

• d) Malaria → Shows ring forms or other parasitic stages inside RBCs, not echinocytes as a primary feature.

• Basophilic stippling appears as diffuse, blue-purple granular inclusions in red blood cells on a Wright-Giemsa stain.

• It represents aggregates of ribosomal RNA.

• It is classically associated with lead poisoning, as lead inhibits the enzyme that degrades ribosomal RNA. It is also seen in other conditions like thalassemia and myelodysplastic syndromes.

The other options are incorrect:

• b) Iron deficiency anemia → Shows microcytic, hypochromic cells, not basophilic stippling.

• c) G6PD deficiency → Shows bite cells and Heinz bodies (with special stain) during hemolytic crises, not typically basophilic stippling.

• d) Hemolysis → This is a broad category; basophilic stippling is not a general feature of hemolysis.

• Smudge cells (or basket cells) are fragile lymphocytes that rupture during slide preparation, appearing as smeared, disrupted nuclei on a peripheral blood smear.

• They are characteristic of CLL because the malignant lymphocytes in CLL are often more fragile than normal lymphocytes.

• Their presence is a common, almost classic, finding on the peripheral blood smear of a patient with CLL.

The other options are incorrect:

• b) AML → Shows myeloblasts, sometimes with Auer rods, not smudge cells.

• c) ALL → Shows lymphoblasts, which are generally not associated with smudge cells to the same degree.

• d) Hodgkin lymphoma → Diagnosis is based on lymph node biopsy (Reed-Sternberg cells), not peripheral blood smudge cells

• When an automated hematology analyzer flags for “immature granulocytes” (which may include promyelocytes, myelocytes, and metamyelocytes), the standard procedure is to perform a peripheral blood smear review.

• This involves a manual differential count to confirm the presence, quantify, and identify the types of immature granulocytes.

• This is critical for detecting conditions like infection, inflammation, myeloid neoplasms, or bone marrow stress.

The other options are incorrect:

• a) Reticulocyte count → Used to assess erythropoietic activity, not to evaluate immature granulocytes.

• c) Pathologist review → May be needed later if abnormal or diagnostic cells are found, but it is not the first step.

• d) Repeat analysis on a warmed specimen → This is done for cold agglutinin interference, not for an immature granulocyte flag.

• Howell-Jolly bodies are small, round, dark purple inclusions composed of residual nuclear DNA fragments.

• They are normally removed by the spleen, so their presence indicates hyposplenism (e.g., after splenectomy) or impaired splenic function.

The other options are incorrect:

• a) Pappenheimer bodies → Represent iron-containing granules (ferritin aggregates).

• b) Heinz bodies → Represent denatured hemoglobin (visible only with supravital staining).

• d) Basophilic stippling → Represents aggregated ribosomal RNA.

• A leukemoid reaction is a benign, exaggerated leukocyte response (often with WBC count > 50,000/µL) that can mimic chronic myeloid leukemia (CML) or other leukemias.

• The Leukocyte Alkaline Phosphatase (LAP) score is a key test to distinguish them:

  • Leukemoid reaction: High LAP score

  • Chronic Myeloid Leukemia (CML): Low LAP score

The other options are incorrect:

• b) Low LAP score → This is characteristic of CML, not a leukemoid reaction.

• c) Presence of blasts → While a few blasts may be seen in a leukemoid reaction, a high percentage is indicative of acute leukemia.

• d) Smudge cells → These are associated with CLL, not used to distinguish a leukemoid reaction.

• Spherocytes are small, spherical red blood cells that lack the central pallor of normal biconcave discs.

• They are typically seen in:

  1. Hereditary spherocytosis – A genetic membrane defect leading to loss of membrane surface area.

  2. Autoimmune hemolytic anemia – Antibodies against red cell membranes cause partial phagocytosis by splenic macrophages, resulting in spherical cells.

The other options are not typically associated with spherocytes:

• b) Iron deficiency anemia → Microcytic, hypochromic cells.

• c) Thalassemia minor → Microcytic, hypochromic cells, target cells.

• d) Megaloblastic anemia → Macro-ovalocytes.

• Teardrop cells (dacrocytes) and abnormal platelet forms (including large, bizarre-shaped platelets and circulating megakaryocyte fragments) are hallmark findings in primary myelofibrosis.

• This is due to bone marrow fibrosis, which disrupts normal hematopoiesis and causes:

  • Physical distortion of red cells as they squeeze through the fibrotic marrow, resulting in teardrop shapes.

  • Abnormal platelet production and release from extramedullary sites (e.g., spleen).

The other options are incorrect:

• a) Hemolytic anemia → Typically shows spherocytes or schistocytes, not teardrop cells.

• b) G6PD deficiency → Shows bite cells and Heinz bodies during hemolytic crises.

• d) Multiple myeloma → Shows rouleaux formation, not teardrop cells.

• When a blood smear dries too slowly, water tends to evaporate slowly, causing changes in osmotic balance that result in crenation.

• Crenated red cells (echinocytes) have a uniform, shrunken appearance with multiple, short, blunt projections from the cell surface.

• This is a common artifactual change and should not be mistaken for true pathologic red cell shapes.

The other options are less likely or incorrect for slow drying:

• a) Lysed → More associated with hypotonic solutions or physical trauma.

• c) Agglutinated → Caused by antibodies, not drying speed.

• d) Spherocytic → Results from membrane loss in vivo (e.g., hereditary spherocytosis or immune hemolysis), not an artifact of smear preparation.

• Liver disease causes characteristic changes in red blood cell (RBC) morphology due to altered lipid metabolism affecting the RBC membrane.

  • Target cells: Excess cholesterol in the membrane increases the cell’s surface area without a proportional increase in volume, leading to the classic “target” appearance.

  • Acanthocytes (spur cells): In severe liver disease (particularly advanced alcoholic liver disease or cirrhosis), an imbalance of cholesterol and phospholipids can result in these irregular, spiculated RBCs.

The other options are incorrect:

• b) Schistocytes → Associated with microangiopathic hemolytic anemia (e.g., DIC, HUS), not liver disease.

• c) Bite cells → Associated with oxidative hemolysis (e.g., G6PD deficiency).

• d) Hypersegmented neutrophils → Associated with megaloblastic anemia (B12/folate deficiency).

• Howell–Jolly bodies are small, round, dark purple inclusions in red blood cells.

• They represent nuclear DNA remnants that persist after the nucleus is expelled from the normoblast during normal red cell maturation.

• They are usually removed by the spleen, so their presence in peripheral blood suggests hyposplenism (e.g., post-splenectomy) or impaired splenic function.

The other options are incorrect:

• a) RNA remnants → These appear as basophilic stippling, not Howell-Jolly bodies.

• c) Iron deposits → These are visible as Pappenheimer bodies (with Prussian blue stain) or as hemosiderin.

• d) Denatured hemoglobin → This forms Heinz bodies, which are visible with supravital staining, not on a standard Wright-Giemsa smear.

• The Pelger–Huët anomaly is characterized by neutrophils with bilobed or unsegmented (“dumbbell” or “pince-nez”) nuclei and coarse, clumped chromatin.

• It is classically an inherited, benign, autosomal dominant condition with no associated clinical disease.

• An acquired or pseudo-Pelger–Huët anomaly can occur in some conditions like myelodysplastic syndrome (MDS) or acute leukemia, but the question specifies the typical presentation, which is the inherited benign form.

The other options are incorrect:

• a) Acquired from B12 deficiency → B12 deficiency causes hypersegmented neutrophils, not hyposegmented.

• c) Seen in iron deficiency → Iron deficiency does not cause Pelger–Huët cells.

• d) Pathognomonic for leukemia only → Incorrect, as the classic form is benign and inherited.

• Heinz bodies are denatured hemoglobin precipitates that form within red blood cells.

• They are not visible on a routine Wright-Giemsa stain.

• They are best visualized using a supravital stain, such as crystal violet or methyl violet, which stain the Heinz bodies a characteristic purple color.

The other options are incorrect:

• a) Wright stain → Routine stain for general blood cell morphology; Heinz bodies are usually not seen.

• c) Prussian blue → Used to stain iron (e.g., hemosiderin, Pappenheimer bodies).

• d) PAS stain → Used to detect glycogen and carbohydrates, often in certain leukemias or erythroleukemia.

The description is classic for a monocyte:

• Kidney-shaped or folded nucleus

• Lacy, delicate chromatin

• Abundant gray-blue cytoplasm

• Fine azurophilic granules (dust-like) and sometimes vacuoles

The other options are incorrect:

• a) Promyelocyte → Has a round nucleus, prominent nucleoli, and coarse primary (azurophilic) granules, but the chromatin is less lacy and the nucleus is not kidney-shaped.

• c) Myelocyte → Has a round nucleus, no nucleoli, and both primary and secondary (specific) granules; the cytoplasm is more pinkish-tan.

• d) Reactive lymphocyte → Has an irregular (but not typically kidney-shaped) nucleus, dense chromatin, and deeply basophilic (blue) cytoplasm, often with a peripheral rim.

• A spherocyte is a small, spherical red blood cell that lacks central pallor due to a reduced surface-to-volume ratio. This happens when the cell loses membrane without a proportional loss of hemoglobin.

• It is a key finding in hereditary spherocytosis and autoimmune hemolytic anemia.

The other options are incorrect:

• a) Leptocyte → A thin, flattened cell (often a target cell), not spherical.

• c) Codocyte → Another name for a target cell, which has a bull’s-eye appearance and increased central pallor, not lack of pallor.

• d) Dacrocyte → A teardrop cell, which is not spherical.

• Teardrop cells (dacrocytes) are red blood cells with a single pointed extension, resembling a teardrop.

• They are most characteristically seen in myelofibrosis (both primary and secondary). In this condition, fibrosis of the bone marrow distorts the marrow architecture, physically squeezing the red cells as they exit, resulting in their abnormal shape.

• They can also be seen in other myeloproliferative neoplasms, metastatic cancer to the bone marrow, and severe megaloblastic anemia.

The other options are incorrect:

• b) Iron deficiency anemia → Shows microcytic, hypochromic cells, not teardrop cells.

• c) Aplastic anemia → Generally shows normocytic cells without specific teardrop morphology.

• d) Sickle cell anemia → Shows sickle-shaped cells, not teardrop cells.

• Hypersegmented neutrophils are defined as neutrophils with six or more nuclear lobes.

• They are a classic, early laboratory finding in megaloblastic anemia, which is caused by vitamin B12 or folate deficiency. This deficiency impairs DNA synthesis, leading to abnormal nuclear maturation in all cell lines, including neutrophils.

The other options are incorrect:

• b) Hemolytic anemia → Does not characteristically cause hypersegmented neutrophils.

• c) Thalassemia minor → Shows microcytic, hypochromic red cells, not hypersegmented neutrophils.

• d) Polycythemia vera → May show increased neutrophils, but not specifically hypersegmentation.

• Rouleaux formation describes red blood cells that stack together in chains like a pile of coins.

• It occurs when there is an increase in plasma proteins, particularly fibrinogen or immunoglobulins, which reduce the normal repulsion between negatively charged red cell membranes.

• It is classically seen in Multiple Myeloma due to the high levels of monoclonal immunoglobulins (M-proteins).

The other options are less associated with rouleaux:

• b) Hemolysis – Does not typically cause rouleaux; schistocytes or spherocytes are more common.

• c) Thalassemia – Shows target cells and microcytosis, not prominent rouleaux.

• d) Sickle cell anemia – Shows sickled cells, not rouleaux.

• Target cells (codocytes) have a characteristic appearance with a central area of hemoglobin surrounded by a clear ring and an outer rim of hemoglobin.

• They are most commonly associated with:

  1. Hemoglobinopathies like Thalassemia – due to reduced hemoglobin content and altered red cell membrane.

  2. Liver disease – due to increased red cell membrane cholesterol from abnormal lipid metabolism.

The other options are incorrect because:

• b) Iron deficiency anemia – Can sometimes show target cells, but it is not the most common or characteristic finding (microcytosis and hypochromia are more typical).

• c) Aplastic anemia – Usually shows normocytic, normochromic cells without specific poikilocytosis like target cells.

• d) Sickle cell anemia only – Target cells can be seen, but they are not exclusive to sickle cell anemia and are more classically linked with thalassemia and liver disease.

• Crenation refers to RBCs with spiky or scalloped edges (burr cells).

• This can occur as an artifact when a blood smear is made from old EDTA-anticoagulated blood (typically >4–6 hours) because:

  • RBCs lose water and deform over time

  • Cell membranes shrink, producing echinocyte-like morphology

Other options:

• a) Spherocytosis: True morphologic abnormality, seen in hereditary spherocytosis or autoimmune hemolysis, not an artifact of old EDTA.

• c) Platelet satellitism: Rare artifact in EDTA samples due to platelets clumping around neutrophils, unrelated to age of sample.

• d) Rouleaux formation: Usually caused by high plasma proteins, not old EDTA samples.

• Multiple myeloma is characterized by the overproduction of monoclonal immunoglobulins (M-proteins).

• These abnormal proteins coat red blood cells, reducing their normal negative surface charge repulsion and causing them to stack together in chains, a phenomenon known as rouleaux formation.

• This is a classic and frequently observed finding on the peripheral blood smear of patients with multiple myeloma.

The other options are incorrect:

• a) Spherocytosis → Associated with hereditary spherocytosis and autoimmune hemolytic anemia.

• b) Toxic granulation → Seen in severe bacterial infections.

• d) Macro-ovalocytes → Characteristic of megaloblastic anemia.

• Wright–Giemsa stain is the routine stain used for examining peripheral blood smears and bone marrow films.

• It is a type of Romanowsky stain that helps differentiate blood cell types by staining nuclei, cytoplasm, and granules distinctively.

Other options:

• b) Prussian blue stain: Used to detect iron (e.g., sideroblasts, hemosiderin).

• c) PAS stain (Periodic acid–Schiff): Detects glycogen and mucopolysaccharides; used in some leukemias.

• d) Sudan black stain: Stains lipids; used to identify myeloid cells in leukemia.

• Pappenheimer bodies are small, basophilic, iron-containing granules that appear clustered at the periphery of red blood cells on a Wright-Giemsa stain.

• They are composed of ferritin aggregates (non-heme iron) and are visible because of the presence of ribosomes and iron.

• They are confirmed with a Prussian blue stain, which specifically stains iron and will turn these granules blue.

The other options are incorrect:

• a) DNA remnants → These are Howell-Jolly bodies.

• c) RNA granules → This describes basophilic stippling.

• d) Hemoglobin crystals → These are seen in certain hemoglobinopathies like HbC disease, but they are not Pappenheimer bodies.

• Hypogranular neutrophils are neutrophils that appear to have reduced or absent normal cytoplasmic granules.

• This is a common dysplastic feature seen in myelodysplastic syndromes (MDS), where abnormal bone marrow production leads to morphologically abnormal cells.

• The hypogranularity reflects defective granulocyte maturation.

The other options are incorrect:

• b) Iron deficiency anemia → Affects red blood cells, not neutrophil granulation.

• c) Polycythemia vera → May show increased neutrophils, but not typically hypogranularity.

• d) Viral infections → Usually cause lymphocytosis or atypical lymphocytes, not hypogranular neutrophils.

The combination of microspherocytes and schistocytes on a peripheral blood smear is highly characteristic of thermal burns.

• Microspherocytes form when heat causes fragmentation and loss of red cell membrane, resulting in spherical, smaller cells.

• Schistocytes (fragmented RBCs) occur due to direct physical damage and shearing of red cells from the heat injury.

This specific combination is a classic finding in patients with extensive burns.

The other options are incorrect:

• a) Hereditary spherocytosis → Shows spherocytes, but not schistocytes.

• b) Thalassemia major → Shows microcytic, hypochromic cells, target cells, and nucleated RBCs, not spherocytes and schistocytes.

• d) Iron deficiency anemia → Shows microcytic, hypochromic cells, not spherocytes or schistocytes.