Magnetic resonance imaging findings of sclerosing microcystic adenocarcinoma: A case report and review of the literature.

Sclerosing microcystic adenocarcinoma (SMA) is a rare malignant tumor of the salivary glands that closely resembles cutaneous microcystic adnexal carcinoma (MAC). It was newly listed in the 5th edition of the WHO classification of head and neck tumors. This report describes the case of a 61-year-old woman who presented with masses on the floor of the mouth. The masses showed low signal intensity on T2-weighted images (T2WI) and with low apparent diffusion coefficient (ADC) values. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) revealed a plateau or persistence after rapid initial enhancement. Histopathologically, the tumors comprised small infiltrating strands of cells that formed small ducts and cysts embedded in thick fibrous stroma, consistent with SMA. Low signal intensity on T2WI with a low ADC value and a plateau or persistence after rapid initial enhancement on DCE-MRI reflect the fibrous and cellular components of the tumor and can be considered characteristic MRI findings of SMA.