BCSE Pathology 3 — Questions and Answers
Question 1: A 25-year-old woman presents with a painless neck mass. Biopsy shows lymphocytes, plasma cells, eosinophils, and Reed-Sternberg cells. What is the most likely diagnosis?
- Non-Hodgkin lymphoma
- Hodgkin lymphoma (Correct answer)
- Reactive lymphadenitis
- Metastatic carcinoma
Correct answer: Hodgkin lymphoma
Reed-Sternberg cells (large binucleate cells with prominent 'owl-eye' nucleoli) are the pathognomonic hallmark of Hodgkin lymphoma.
Question 2: Which type of hypersensitivity reaction underlies contact dermatitis caused by poison ivy?
- Type I (IgE-mediated)
- Type II (cytotoxic)
- Type III (immune complex)
- Type IV (delayed/cell-mediated) (Correct answer)
Correct answer: Type IV (delayed/cell-mediated)
Contact dermatitis is a Type IV (delayed-type) hypersensitivity reaction mediated by sensitized CD4+ T cells, not antibodies.
Question 3: A newborn has ambiguous genitalia. Karyotype is 46,XX. Serum 17-hydroxyprogesterone is markedly elevated. Which enzyme deficiency is most likely?
- 21-hydroxylase (Correct answer)
- 11β-hydroxylase
- 17α-hydroxylase
- 3β-hydroxysteroid dehydrogenase
Correct answer: 21-hydroxylase
21-hydroxylase deficiency is the most common cause of congenital adrenal hyperplasia and causes virilization of female fetuses due to androgen excess.
Question 4: On histology, a thyroid nodule shows cells arranged in follicles with 'Orphan Annie eye' nuclei and nuclear grooves. What is the diagnosis?
- Follicular carcinoma
- Papillary carcinoma (Correct answer)
- Medullary carcinoma
- Anaplastic carcinoma
Correct answer: Papillary carcinoma
Papillary thyroid carcinoma is characterized by 'Orphan Annie eye' (empty-appearing) nuclei, nuclear grooves, and psammoma bodies.
Question 5: A 70-year-old man is found to have a left renal mass on CT. Microscopically the tumor shows clear cells with abundant lipid and glycogen. What is the most likely diagnosis?
- Transitional cell carcinoma
- Wilms tumor
- Clear cell renal cell carcinoma (Correct answer)
- Oncocytoma
Correct answer: Clear cell renal cell carcinoma
Clear cell renal cell carcinoma is the most common renal malignancy in adults and shows characteristic clear cytoplasm due to lipid and glycogen accumulation.
Question 6: Which pattern of inheritance is demonstrated by achondroplasia, where the disease manifests even with only one mutant allele?
- Autosomal recessive
- X-linked recessive
- Autosomal dominant (Correct answer)
- Mitochondrial
Correct answer: Autosomal dominant
Achondroplasia follows autosomal dominant inheritance due to a gain-of-function FGFR3 mutation; one copy is sufficient to cause the disease.
Question 7: A patient develops fever, rash, and joint pain 10 days after receiving antithymocyte globulin (horse serum). Biopsy of the rash shows vascular immune complex deposition. This reaction exemplifies:
- Type I hypersensitivity
- Type II hypersensitivity
- Type III hypersensitivity (Correct answer)
- Type IV hypersensitivity
Correct answer: Type III hypersensitivity
Serum sickness is the classic Type III (immune complex-mediated) hypersensitivity reaction, where antigen-antibody complexes deposit in tissues and activate complement.
BCSE Pathology 3
A 25-year-old woman presents with a painless neck mass.
Biopsy shows lymphocytes, plasma cells, eosinophils, and Reed-Sternberg cells.
What is the most likely diagnosis?