Salivary duct
carcinoma (SDC) is a highly aggressive salivary gland
carcinoma, and the
mucin-rich variant of SDC (
mSDC) is extremely rare. We report herein one case of salivary
mSDC, showing predominantly signet-ring cell features. The patient was an 84-year-old Japanese woman, who noticed swelling in the left submandibular region. The
tumor consisted of two components: one was of
mSDC, which contained numerous signet-ring cells in large mucinous lakes, whereas the other was of preexisting
pleomorphic adenoma (PA), which showed a hyalinized nodule.
mSDC was markedly positive for
mucin staining. Signetring cells in the
mSDC component were immunopositive for
androgen receptor, gross cystic disease fluid protein-15, MUC1, MUC2, MUC5AC, MUC5B, and MUC6, but negative for Her-2 and myoepithelial markers. This case was diagnosed as
mSDC with the signet-ring cell feature ex PA. We discuss herein the significance of the signet-ring cell feature in
mSDC and the
mucin pattern of
mSDC.