General Pathology USMLE Step 1 Practice Question
A 47-year-old woman presents with a 1.2-cm irregularly pigmented lesion on her upper back that has enlarged over 6 months. Vital signs are normal (BP 128/82, HR 72, RR 16, Temp 37°C). She denies constitutional symptoms and has no relevant medication history. Excisional biopsy confirms melanoma with 0.8-mm Breslow thickness. Histology shows atypical melanocytes with increased mitotic activity; S-100 protein is positive. Which additional immunohistochemical marker is most likely positive in this tumor?
Answer choices
- APSA
- BCD31
- CS 100Correct answer
- DCytokeratin only
- ETRAP
- FSynaptophysin
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