A case of minor salivary gland mucinous adenocarcinoma metastasis to the submandibular gland

Abstract

Mucinous adenocarcinoma is a salivary gland carcinoma characterized by mucin production without the features of other salivary gland tumor types.　The patient was an elderly man in his 80s with masses on the right upper lip and right submandibular area.　Histologically, both tumors were adenocarcinomas showing papillary and tubular growth patterns composed of tall columnar epithelial cells.

Immunohistochemically, the tumor cells were positive for NKX3.1, MUC5AC and MUC5B, and showed diffuse, strong positivity for p53.　Sanger sequencing revealed an AKT1 p.Glu17Lys gene variant.　Although Alcian blue-PAS-positive-mucinous cells were limited to 10% of the tumor cells, this case was diagnosed as mucinous adenocarcinoma originating from the right upper lip after excluding other tumor types.

Mucinous adenocarcinoma demonstrates a broad histological spectrum, with varying mucinous cell ratio.　The update of diagnostic criteria and tumor classification are warranted.