Signet-ring cell change in adenoid cystic carcinoma: a clinicopathologic and immunohistochemical study of four cases.

Abstract

Signet-ring cell (SRC) change has not been reported in adenoid cystic carcinomas (ACC). This study describes the clinicopathological and immunohistochemical findings in four cases of ACC with SRCs (ACC-SRC), in which the relative proportion of the SRC component ranged from 25% to 50%. The median age was 58 years (range: 48 to 81 y) and all patients were women. The involved sites were sinonasal, lip and submandibular. Two patients developed lung metastasis and one died of disease 63 months after tumor resection. Neither mucinous nor lipid substances were detected in the SRCs. These were positive for AE1/AE3, CK14 and EMA; which highlighted the intracytoplasmic vacuole borders. The SRC nests were surrounded by α-SMA and p63 positive myoepithelial cells. When compared to the conventional component, the SRCs exhibited similar p53 positivity but lower Ki-67 and mitotic indices. SRCs were C-Myb negative. Ultrastructural examination revealed that the intracytoplasmic vacuoles were lumens lined by microvilli. ACC-SRC is a nonmucin and nonlipid producing phenomenon, possibly related to disturbed differentiation of ductal/luminal cells. This cellular modification in ACC apparently does not change the biological behavior of the tumor but it may cause significant diagnostic problems, particularly in incisional biopsies. © 2012 Blackwell Publishing Ltd.