The profile of acinic cell carcinoma after recognition of mammary analog secretory carcinoma

Abstract

To determine the influence of the newly described mammary analog secretory carcinoma (MASC) with ETV6 translocation on our understanding of salivary acinic cell carcinoma (AciCC), we reviewed 81 cases of AciCC: 64 "classic" AciCCs, 11 AciCCs with high-grade transformation (HGT), and 17 zymogen granule poor AciCCs. ETV6 fluorescence in situ hybridization revealed that classic AciCC (7 of 7 tested) and AciCC-HGT (4 of 4 tested) have intact ETV6. However, 10 of 17 zymogen granule poor AciCCs showed ETV6 translocation and were reclassified as MASC; the diagnosis of AciCC was retained for cases with intact ETV6. MASCs were distinguished by the lack of zymogen granules, mucin production, and stronger S100 reactivity. MASC showed a striking male predilection (male-to-female ratio, 8:2) in contrast to AciCC (male-to-female ratio, 1:1.5; P<0.01). Compared with cases of confirmed AciCC, AciCC-HGT occurred in older patients (mean age of 66.2 y vs. 47.7 y, P=0.007) and showed a poorer mean overall survival [40.2 mo (95% confidence interval (CI), 7.5-73 mo) vs. 125 mo (95% CI: 98-151 mo); P<0.001]. Patients with confirmed AciCC without HGT showed a recurrence rate of 15% (9/60) and a 7.9% (3/38) incidence of regional lymph node involvement. It appears that more than half of zymogen granule poor AciCCs are likely to represent MASC. Even after excluding cases of MASC, the presence of HGT in AciCC predicts poorer overall survival.