First Description of a Hybrid Tumor of the Sublingual Gland

A: Hybrid tumour of the sublingual gland. The component of adenoid cystic carcinoma (upper part) exhibits a predominant tubular and cribriform architecture. The salivary duct carcinoma (lower part) forms large duct-like structures with a solid pattern and central comedo-like necrosis with parafocal chronic inflammation. Hematoxylin and eosin, ×50. B: Salivary duct carcinoma (left side) with a duct filled by large, pleomorphic tumour cells in a solid pattern and central comedo-like necrosis. Adenoid cystic carcinoma (right side) is sharply demarcated with smaller tumour cells arranged in tubular and cribriform glands. HE, ×200. C: Immunohistochemical analysis showed strong expression of the myoepithelial marker p63 in the adenoid cystic carcinoma and only focal expression in the salivary duct component. ×100. D: Strong expression of cytokeratin 5/6 by immunohistochemistry in the adenoid cystic component and only weak restricted staining in the salivary duct carcinoma. ×100.