TUMOR-SIMULATING SQUAMOUS-CELL METAPLASIA (SCM) IN NECROTIC AREAS OF SALIVARY-GLAND TUMORS

Squamous cell metaplasia (SCM) adjacent to necrotic areas of salivary gland tumours must be distinguished from other types of SCM (focal SCM in the excretory ducts of salivary glands, necrotizing sialometaplasi a; focal SCM within salivary gland rumours) in respect to the tissue s tructure. Based on the high cellular proliferation, arcade-or cord-lik e pseudoneoplastic SCM develops with stellate extension in the surroun ding tissue and focal inclusion of goblet cell metaplasia. This prolif erative SCM resembles the cellular demarcation of radicular dental cys ts. In the Salivary Gland Register 8 cases of tumour-simulating SCM co uld be analysed which clinically and morphologically were suspect of s quamous cell or mucoepidermoid carcinoma. Five cases were localized in the parotid gland, 2 cases in the submandibular,oland and 1 case in t he palatinal glands. Tumour-simulating SCM was developed in pleomorphi c adenomas (5 cases) and in multifocal adenomatous oncocytic hyperplas ia (3 cases).