Basaloid squamous carcinoma with collagenous spherules and crystalloids.

A case of basaloid squamous carcinoma with unusual spheruloid and crystalloid structures occurring in the left submandibular region of 45-year-old woman is described. The tumor displayed features typical of basaloid squamous carcinoma. In addition, there were numerous eosinophilic deposits of extracellular matrix, which reacted positively on periodic acid-Schiff staining. These deposits were arranged in lamellar concentric and radial patterns. Ultrastructurally, they were composed of extracellular matrix components rich in basement membrane substances. A few banded collagen fibers were found in some deposits. Basaloid squamous carcinoma is an aggressive variant of squamous cell carcinoma, with a predilection to the head and neck region, that needs to be distinguished from other tumors that may contain abundant deposits of basement membrane rich material, especially from adenoid cystic carcinoma.