A 28-year-old man presents with a painless testicular mass. Histology shows uniform cells with clear cytoplasm and central nuclei, arranged in sheets with lymphocytic infiltrate in the septa. Immunohistochemistry is positive for OCT3/4 and CD117 (c-KIT), and negative for AFP and hCG. Which translocation is most commonly associated with this tumor type?
- A i(12p) ✓
- B t(12;16)(q13;p11)
- C t(11;17)(q23;q21)
- D t(X;18)(p11;q11)
Correct answer: A. i(12p)
Explanation
The histology and immunoprofile (OCT3/4+, CD117+, AFP-, hCG-) are classic for seminoma. Isochromosome 12p (i(12p)) is the characteristic cytogenetic abnormality found in over 80% of seminomas and other germ cell tumors. t(12;16) is seen in myxoid liposarcoma. t(X;18) is seen in synovial sarcoma. t(11;17) is seen in acute promyelocytic leukemia.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.