Mucosal adenoid squamous cell carcinoma of the head and neck.

Adenoid squamous cell carcinoma is an uncommon variant of squamous cell carcinoma. The lesion is histologically distinctive and it is usually localized on the skin of the head and neck region; it only rarely involves the mucosal sites. The differential diagnoses include adenosquamous carcinoma, adenoid cystic carcinoma, mucoepidermoid carcinoma, basaloid squamous cell carcinoma, and metastatic adenocarcinoma. Surgery is the treatment of choice. The biologic behavior of this neoplasm is more aggressive when it involves mucosal areas, and the prognosis seems worse than that of conventional squamous cell carcinoma.