Case 51
- Wangpan Shi
- Feb 19
- 2 min read
A 56-year-old male was found to have a testicular mass.
1. Which of the following features is characteristic of GCNIS cells?
A) Small, round nuclei with fine chromatin
B) Ample clear cytoplasm and large angulated nuclei with coarse chromatin
C) Multiple nucleoli and darkly stained cytoplasm
D) Presence of eosinophilic cytoplasmic granules
Answer
B) Ample clear cytoplasm and large angulated nuclei with coarse chromatin
Explanation: GCNIS cells resemble gonocytes and have clear cytoplasm with large, angulated nuclei. They usually contain one nucleolus and exhibit coarse chromatin.
2. What is the most common genetic alteration observed in invasive TGCT but not in GCNIS?
A) Loss of chromosome 3p
B) Gain of chromosome 12p (typically isochromosome 12p)
C) TP53 mutation
D) Loss of function mutation in BRCA1
Answer
B) Gain of chromosome 12p (typically isochromosome 12p)
Explanation: Invasive TGCTs consistently show gain of chromosome 12p, whereas this alteration is not seen in GCNIS.
3. Which of the following genetic mutations is more commonly found in seminomas than in NSGCTs?
A) BRCA1 mutations
B) KIT and KRAS activating mutations
C) TP53 loss-of-function mutations
D) APC mutations
Answer
B) KIT and KRAS activating mutations
Explanation: Activating mutations in KIT and KRAS are more frequently observed in seminomas than in NSGCTs.
What type of karyotype is typically observed in both TGCT and GCNIS cells?
A) Diploid
B) Aneuploid (hypertriploid to subtetraploid)
C) Monosomy 7
D) Loss of chromosome Y
Answer
B) Aneuploid (hypertriploid to subtetraploid)
Explanation: Both TGCT and GCNIS cells are typically aneuploid, with hypertriploid to subtetraploid karyotypes.
GCNIS
Essential Feature:
Neoplastic gonocytes located in the spermatogonial niche of seminiferous tubules.
Arranged in a string-of-beads pattern.
Desirable Features:
Positive immunohistochemistry for:
OCT4
KIT
PLAP
SOX17
NANOG
Podoplanin
Case credit: UCSD Pathology
Author: Wangpan Jackson Shi, MD
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