FMGE 2024 - Pathology PYQs Practice Questions

Q: Which blood is transfused in a patient with a Bombay blood group?

O negative. ⚠️ **IMPORTANT CLINICAL NOTE**: Patients with Bombay blood group (Oh phenotype) can **ONLY safely receive Bombay (Oh) blood** from another Bombay donor. **None of the standard ABO blood types listed below are correct or safe** for transfusion. ***Bombay Blood (Oh) - THE ONLY CORRECT ANSWER (Not Listed)*** - Bombay patients lack the **H antigen** due to deficiency of fucosyltransferase enzyme - They produce potent **anti-H, anti-A, and anti-B antibodies** [1] - **Only Bombay (Oh) blood is compatible** - this is the true correct answer - Standard blood banks must maintain rare Bombay donor registries for these patients **Why the listed options are ALL incorrect:** *O negative (Marked as "correct" but clinically WRONG)* - O negative blood **contains the H antigen**, which is present in all standard ABO groups [1] - Transfusing O negative to a Bombay patient causes **severe acute hemolytic transfusion reaction** due to anti-H antibodies - While O negative lacks A and B antigens, the presence of **H antigen makes it incompatible and dangerous** - This is a common misconception that must be avoided in clinical practice *A* - Contains **A antigen and H antigen** - Causes immediate hemolytic reaction from both **anti-A and anti-H antibodies** - Completely incompatible *B* - Contains **B antigen and H antigen** [1] - Causes rapid hemolysis from both **anti-B and anti-H antibodies** - Completely incompatible *AB* - Contains **A antigen, B antigen, and H antigen** - Causes massive hemolytic reaction from all three antibodies - Most incompatible of all standard blood types **Clinical Pearl**: Bombay phenotype is rare (~1 in 10,000 in India). Always maintain autologous blood storage or identify compatible Bombay donors in advance for these patients. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 627-628. [Practice more Pathology PYQs on OnCourse]

Q: Which of the following is the investigation of choice for CML?

Karyotyping. ***Karyotyping (Conventional Cytogenetics)*** - **Gold standard** and investigation of choice for CML diagnosis - Detects the **Philadelphia chromosome t(9;22)** present in 95% of CML cases [2] - WHO diagnostic criterion for CML - Can identify additional chromosomal abnormalities with prognostic significance - Provides complete chromosomal analysis *FISH (Fluorescence In Situ Hybridization)* - Used as **complementary technique** when karyotyping fails or metaphases are inadequate - More sensitive than karyotyping but NOT the first-line investigation [2] - Useful for monitoring minimal residual disease - Cannot detect additional chromosomal abnormalities *Molecular testing (BCR-ABL PCR)* - Used for **monitoring treatment response** and detecting minimal residual disease [1] - Highly sensitive and quantitative [1] - Not the initial investigation of choice for diagnosis *LAP score (Leukocyte Alkaline Phosphatase)* - Used to differentiate CML from leukemoid reaction - Low in CML, high in leukemoid reaction - Older diagnostic tool, now largely replaced by molecular methods - Not the investigation of choice **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Genetic Disorders, pp. 185-187. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 225-226. [Practice more Pathology PYQs on OnCourse]

Q: A 5-year-old child presents with a lesion in the right eye. Histopathology reveals the presence of Flexner-Wintersteiner rosettes. What is the likely diagnosis?

Retinoblastoma. ***Retinoblastoma*** - The presence of **Flexner-Wintersteiner rosettes**, which are characteristic arrangements of columnar cells around a central lumen, is the pathognomonic histological feature of well-differentiated **retinoblastoma** [1].- This tumor is the most common **intraocular malignancy** of childhood, typically presenting as **leukocoria** (white pupillary reflex) in children under the age of 5. *Optic nerve glioma*- These tumors are typically low-grade astrocytomas, most frequently **pilocytic astrocytomas**, characterized by glial cells, not neuronal-like rosettes.- They involve the **optic nerve** itself and are strongly associated with **Neurofibromatosis type 1 (NF1)**. *Rhabdomyosarcoma*- This is the most common **pediatric orbital malignancy** (outside the globe), typically presenting with rapid onset of **proptosis** (exophthalmos) and eyelid swelling.- Histologically, it is a small round blue cell tumor derived from mesenchymal cells, showing **rhabdomyoblasts**, and does not form Flexner-Wintersteiner rosettes. *Ocular melanoma*- This malignancy is extremely rare in the pediatric population and is overwhelmingly a disease of **adults**.- Histopathology shows malignant cells derived from **melanocytes** (spindle or epithelioid cells) containing melanin, lacking photoreceptor differentiation structures like rosettes. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Eye, p. 1342. [Practice more Pathology PYQs on OnCourse]

Question 1

Which blood is transfused in a patient with a Bombay blood group?

Accepted Answer

O negative

Answer

A

Answer

AB

Answer

B

Question 2

A 10-year-old boy is brought to the ED after being stung by a bee while playing outside. Within minutes of the sting, he developed shock, respiratory failure, and vascular collapse. What type of hypersensitivity reaction is most likely responsible?

Accepted Answer

A. IgE-mediated reaction

Answer

D. T cell-mediated response

Answer

B. IgG-mediated reaction

Answer

C. IgA-mediated hypersensitivity

Question 3

Which of the following is the investigation of choice for CML?

Accepted Answer

Karyotyping

Answer

LAP score

Answer

FISH

Answer

Molecular testing (BCR-ABL PCR)

Question 4

A 5-year-old child presents with a lesion in the right eye. Histopathology reveals the presence of Flexner-Wintersteiner rosettes. What is the likely diagnosis?

Accepted Answer

Retinoblastoma

Answer

Optic nerve glioma

Answer

Rhabdomyosarcoma

Answer

Ocular melanoma

FMGE 2024 — Pathology