Friday Pop Quiz #41

dermal mass

The answer is B. B. TTF-1.

The pictured image is that of merkel cell carcinoma (MCC), a rare highly aggressive malignant neuroendocrine carcinoma. In order to differentiate MCC from small cell lung carcinoma (SCLC; aka Oat cell carcinoma), another malignant neuroendocrine carcinoma, histologic staining with TTF-1 is most helpful. This is because MCC (nearly always) stains negative for TTF-1, whereas SCLC stains positive for TTF-1. The remaining answer choices will be positive in both MCC and SCLC, so they cannot be used to differentiate between the two malignancies.

Brought to you by our Brand Partner
Derm In-Review