Imaging diagnosis of mucoepidermoid carcinoma with intratumoral bone formation: a case report

Mucoepidermoid carcinoma (MEC) is the most frequent salivary gland malignancy. Rarely, intra tumor bone formation may occur. To date there have been only two reports of MEC with bone formation in the oral and maxillofacial region. We report a case of MEC in the sublingual gland with intratumor bone formation involving a 78-year-old woman. The study presents the imaging findings of the lesion across multiple modalities. Multi-detector row computed tomography (MDCT) imaging revealed a 21 × 18 × 12 mm mass in the left side of floor of the mouth, containing multiple calcified-like high CT numbers (≥ 400 HU). Magnetic resonance imaging (MRI) revealed a 28 × 21 × 11 mm mass that was isointense to muscle on T1-weighted images, intermediate signal intensity on short tau inversion recovery (STIR) images and with heterogeneous contrast enhancement. In addition, multiple signal voids suspicious for calcification were observed inside the lesion. Ultrasonography showed a well-defined hypoechoic lesion within the left sublingual gland and multiple hyperreflective bodies with acoustic shadows inside the lesion. Histopathologically, the lesion was diagnosed as intermediate-grade MEC with bone formation inside the lesion. The identification of calcifications on the MDCT examination was a key prompt to further investigate the nature of the lesion.