Sclerosing microcystic adenocarcinoma of the tongue: a report of 2 further cases and review of the literature.

We present 2 further cases of sclerosing microcystic adenocarcinoma occurring in the tongue in 2 female patients, one age 68 years and the other 49 years. Histopathologically, both tumors were characterized by a diffusely infiltrative lesion consisting of small cuboidal cells arranged in discrete dispersed cords, isolated tubules, and bilayered strands with intervening microcystic lumina set in a sclerotic background. Both lesions showed striking neurotropism with perineural and intraneural infiltration. Extensive invasion of adjacent skeletal muscle was also observed. The tumor cells showed diffuse staining with antibodies to cytokeratin 7 (CK7). A dual population of ductal and myoepithelial cells was identified, with antibodies to CAM5.2 and CK5/6 decorating the inner epithelial layer and antibodies to p63, p40, and S100 staining the outer myoepithelial cell layer. The Ki-67 proliferation index in both cases was less than 5%. An initial diagnosis of adenocarcinoma NOS (not otherwise specified) of salivary gland origin was made on both incisional biopsies and a possible metastatic origin, particularly from the breast, also raised. A local minor salivary gland origin was confirmed after staging investigations and surgical resection. Both patients were t.