Answer: Squamous carcinoma associated with Inverted papilloma

Histology: The lesion is predominantly composed of papillary fronds lined by squamous epithelium with highly atypical nuclear features and brisk mitotic activity. Background exophytic and inverted papillary structures lined by thickened respiratory to “transitional” epithelium without significant nuclear atypia are focally seen, containing dense neutrophilic inflammatory infiltrates typical of Inverted (Schneiderian) Papilloma. No definitive evidence of invasion was demonstrated in this entirely submitted tumor.

Discussion: The association of invasive squamous carcinoma with inverted papillomas is a relatively rare event that has been described in 5-15% of papillomas. The associated carcinoma tends to occur in patients that are on average a decade older than those with benign inverted papillomas. There are no criteria that can help predict which inverted papillomas are more likely to develop carcinoma. The carcinoma can be diagnosed at the time of first diagnosis or following one or multiple recurrences of an inverted papilloma.