Hematopathology Practice Questions

Q: Which immunohistochemistry marker is characteristic of histiocytosis X?

CD1a. **Explanation:** **Histiocytosis X**, now more commonly known as **Langerhans Cell Histiocytosis (LCH)**, is a clonal proliferation of Langerhans cells [1]. These cells are specialized dendritic cells normally found in the skin and mucosa. **Why CD1a is the correct answer:** Langerhans cells are characterized by the expression of specific surface markers that aid in their identification. **CD1a** and **Langerin (CD207)** are the most specific immunohistochemical markers for LCH [1]. CD1a is a glycoprotein structurally related to MHC molecules and is essential for the definitive diagnosis of this condition. **Analysis of Incorrect Options:** * **CD57:** This is a marker primarily used for **Natural Killer (NK) cells** and certain neuroendocrine tissues. It has no diagnostic utility in LCH. * **CD3:** This is the definitive pan-**T-cell marker**. While T-cells may be present in the inflammatory background of LCH lesions, the neoplastic cells themselves are CD3 negative. * **CD68:** This is a general marker for **macrophages/monocytes**. While LCH cells may show weak positivity for CD68, it is non-specific and found in various other histiocytic disorders (like Sinus Histiocytosis). It is not diagnostic for LCH. **High-Yield Clinical Pearls for NEET-PG:** * **Electron Microscopy:** The pathognomonic finding is the **Birbeck Granule**, a "tennis-racket" shaped pentalaminar cytoplasmic organelle [1]. * **S100 Protein:** LCH cells are almost always **S100 positive** (though this is non-specific). * **Clinical Triad (Hand-Schüller-Christian disease):** Calvarial bone defects, exophthalmos, and diabetes insipidus. * **Letterer-Siwe Disease:** The aggressive, multisystem form seen in infants (<2 years). **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of White Blood Cells, Lymph Nodes, Spleen, and Thymus, pp. 629-630.

Q: Post-transplant lymphoproliferative disorder is most commonly associated with which cell type?

B cell. **Explanation:** Post-transplant lymphoproliferative disorder (PTLD) refers to a spectrum of conditions ranging from benign lymphoid hyperplasia to malignant lymphoma occurring in patients following solid organ or hematopoietic stem cell transplantation. **Why B cell is correct:** The vast majority (**>85-90%**) of PTLD cases are of **B-cell origin**. The primary driver is the **Epstein-Barr Virus (EBV)**. In the setting of therapeutic immunosuppression (especially T-cell depletion), the host’s cytotoxic T-cells can no longer control EBV-infected B-cells [1]. This leads to the unchecked proliferation of EBV-transformed B-lymphocytes, which can progress from polyclonal expansions to monoclonal B-cell lymphomas (most commonly Diffuse Large B-cell Lymphoma). **Why other options are incorrect:** * **T cell:** While T-cell PTLDs do exist, they are rare (<10-15% of cases), typically occur later after transplantation, and are often not associated with EBV. * **NK cell:** These are extremely rare subtypes of PTLD. * **Null cell:** This term refers to lymphocytes lacking traditional B or T cell surface markers; they do not represent the standard pathology of PTLD. **High-Yield Clinical Pearls for NEET-PG:** * **Most common viral association:** EBV (Epstein-Barr Virus) [1]. * **Risk Factors:** Degree of immunosuppression, EBV-seronegative recipient receiving an organ from an EBV-seropositive donor (primary infection). * **Management:** The first line of management is often the **reduction of immunosuppressive therapy**, which allows the host immune system to recover and target the proliferating B-cells. * **Common Histology:** Diffuse Large B-cell Lymphoma (DLBCL) is the most frequent morphological subtype. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 368-369.

Question 1

Hypersegmented neutrophils are characteristic findings in which of the following conditions?

Accepted Answer

Megaloblastic anemia

Answer

Microcytic hypochromic anemia

Answer

Sideroblastic anemia

Answer

Hemolytic anemia

Question 2

Translocation (8;14) is characteristic of which of the following conditions?

Accepted Answer

Burkitt's lymphoma

Answer

Ataxia telangiectasia

Answer

Acute lymphoblastic leukemia (ALL)

Answer

Chronic myeloid leukemia (CML)

Question 3

Which malignant tumor is associated with Waldenstrom macroglobulinemia?

Accepted Answer

Lymphoplasmacytic lymphoma

Answer

Smoldering myeloma

Answer

Primary effusion lymphoma

Answer

Mycosis fungoides

Question 4

Which of the following tests does NOT assess platelet function?

Accepted Answer

Prothrombin time

Answer

Bleeding time

Answer

Clot retraction time

Answer

Prothrombin deactivation

Question 5

What are the essential WHO criteria for polycythemia vera?

Accepted Answer

Tyrosine kinase JAK2 V617F and other mutations

Answer

Low levels of erythropoietin

Answer

Thrombocytosis

Answer

Increased MCV

Question 6

Which immunohistochemistry marker is characteristic of histiocytosis X?

Accepted Answer

CD1a

Answer

CD57

Answer

CD3

Answer

CD68

Question 7

Beta-2 microglobulin is a marker for which condition?

Accepted Answer

Multiple Myeloma

Answer

Mycosis fungoides

Answer

B-Cell lymphoma

Answer

Mantle cell lymphoma

Question 8

For acute leukemia, the blast cell count should be greater than what percentage?

Accepted Answer

20%

Answer

10%

Answer

30%

Answer

40%

Question 9

Post-transplant lymphoproliferative disorder is most commonly associated with which cell type?

Accepted Answer

B cell

Answer

T cell

Answer

Null cell

Answer

NK cell

Question 10

A patient presents with painless lymphadenopathy. A biopsy reveals binucleated owl-shaped nuclei with a clear vacuolated area. Immunohistochemistry shows positivity for CD15 and CD30. What is the most probable diagnosis?

Accepted Answer

Nodular sclerosis

Answer

Large granular lymphocytic lymphoma

Answer

Lymphocyte depletion type

Answer

Lymphocyte predominant Hodgkin lymphoma

Hematopathology — MCQs

Hematopathology — MCQs

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