Fig. 1

Hematoxylin and eosin stained sections demonstrated a population of tumor cells with minimal cytoplasm, a high nuclear-cytoplasmic ratio, speckled chromatin, nuclear molding, and prominent mitotic and apoptotic figures, consistent with small cell carcinoma (a, 400×). These cells demonstrated patchy positivity for the neuroendocrine marker synaptophysin (b, 400×) and diffuse, strong nuclear and cytoplasmic positivity for p16 (c, 400×) by immunohistochemistry as well as punctate nuclear reactivity for high-risk HPV by RNA in-situ hybridization (d, 400×), supporting the diagnosis of HPV-related small cell carcinoma