Adenosquamous carcinoma of the skin. An aggressive mucin- and gland-forming squamous carcinoma.

Two cases of an aggressive cutaneous carcinoma showed both squamous and adenomatous differentiation. These neoplasms invaded subcutaneous structures with a sclerosing pattern, making surgical resection difficult. Unlike the usual squamous carcinoma, glands and epithelial mucin (sialomucin) were produced. This mucin stained with mucicarmine and was sensitive to sialidase and resistant to hyaluronidase digestion. No mucin with similar histochemical properties was found in a study of 50 consecutive cutaneous squamous carcinomas and 50 consecutive basal cell epitheliomas from our files. Literature reports of histologically similar cutaneous carcinomas together with our experience with these two cases suggest aggressive behavior for this category of neoplasm.