Clinicopathological study of intraductal carcinoma of the salivary gland, with emphasis on the apocrine type

In this study, immunohistochemistry and mutation analyses (includingHRAS/PIK3CA mutations,RET rearrangement, and human epidermal growth factor receptor 2 [HER2] amplification) of 9 ICs (including 3 pure ICs, 6 ICs with invasive carcinoma) and 24 conventional SDCs were performed and the results were compared. Four intercalated duct-type cases were positive for SOX10 and S100 and negative for AR; five apocrine-type cases showed opposite results. All five apocrine-type cases had cysts with relatively circumscribed tumor borders and morphologically mimicking breast low-grade ductal carcinoma in situ or papillary carcinoma.RET fusion is detected in half of the 4 intercalated duct-type IC but not in the apocrine-type or conventional SDC.HER2 amplification was only observed in conventional SDC. The monoclonal antibody (clone RBT-NRAS) against NRAS Q61R is a sensitive and specific marker used for detecting HRAS Q61R mutation in the salivary gland tumors. The apocrine-type IC had different cytological grades, distinct tumor growth patterns, and no evidence of low- to high-grade transition, suggesting that apocrine-type IC should be distinguished from apocrine SDC with an in situ component.
Source: Virchows Archiv - Category: Pathology Source Type: research