Basal cell adenocarcinoma of the salivary gland: a morphological and immunohistochemical comparison with basal cell adenoma with and without capsular invasion

BACKGROUND: It is often difficult to diagnose salivary gland tumors that exhibit basaloid features differentially. The aim of this study was to identify additional morphological and immunohistochemical characteristics that can aid the diagnosis of basal cell adenocarcinoma (BCAC) of the salivary gland. METHODS AND RESULTS: In total, 29 basal cell neoplasms [eight BCACs, 11 basal cell adenomas (BCAs) with capsular invasion, and 10 BCAs without capsular invasion] and 10 cases of adenoid cystic carcinomas (ACCs) were subjected to histopathology and immunohistochemical analyses for CK7, CK5/6, SMA, p63, calponin, p53, c-erbB2, CD117, β-catenin, EGFR, VEGF, Ki-67, and S100P protein expression. Compared to BCA without capsular invasion, the BCACs and BCAs with capsular invasion were more likely to be larger and have solid or cribriform patterns. Most BCACs and BCAs exhibited nuclear β-catenin expression. In all basal cell neoplasm cases, the clinical course after surgery with or without radiotherapy was indolent. β-catenin, CK5/6, CD117, and S100P protein were helpful for differentiating basal cell neoplasms from ACC. CONCLUSIONS: BCAs with capsular invasion shared several pathological features with BCACs, including a large size and frequent cribriform patterns but the malignant potential of these tumors seems highly limited and should be reexamined. β-catenin immunostaining may aid the differential diagnosis between basal cell neoplasms and ACCs. VIRTUAL SLIDES: The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/9637819101988153