Secretory carcinoma of the major salivary gland: a provincial population-based analysis of clinical behavior and outcomes
Abstract
Secretory carcinoma (SC) of the salivary gland, previouslyknown as mammary analog SC, is a recently described tumor, occurring principally in the salivary glands, which resembles SC of the breast and includes a characteristic ETV6 gene rearrangement.1 SC may be distinguished from similar tumors such as acinic cell carcinoma, low-grade intraductal carcinoma, and adenocarcinoma, not otherwise specified (NOS) by few or absent zymogen granules or increased extracellular mucin and by immunohistochemical (IHC) positivity for S-100 protein and mammaglobin.1-6 The diagnosis is confirmed by molecular testing for ETV6 rearrangement by fluorescent in situ hybridization (FISH) or reverse transcription polymerase chain reaction (RTPCR).1-3,5,7,8 The most common reported reciprocal translocation is t(12;15) (p13;q25), which leads to fusion of the ETV6 gene on chromosome 12 and the NTRK3 gene on chromosome 15 although other ETV6 translocation partners have been described.9,10 The resulting ETV6 fusion protein has shown transforming activity in several cell lines11 and has been described in a variety of tumors including secretory breast carcinoma,12 infantile fibrosarcoma,13 congenital mesoblastic nephroma,14,15 and radiation-induced thyroid cancer.16 There are now over 200 published cases of SC since the original description by Skálová in 20101; however, most studi s have reevaluated historical files only of acinic cell carcinoma and other mimickers of SC.5,6,8 Although the histopathology, IHC, and cytology of SC are well characterized, relatively few studies have addressed its clinical behavior with long-term follow-up.1-3,6,7,10,17,18 We present a review of the clinical behavior of cases identified through systematic retrospective review of all malignant salivary gland tumors (MSGTs) presenting to a large provincial health care system.