Salivary Duct Carcinoma

Abstract

Salivary duct carcinoma (SDC) is a prototypic aggressive salivary gland carcinoma. Our aim is to determine the prevalence of histologic variants (micropapillary, basal-like) and androgen receptor (AR) expression in a large multi-institutional series of SDC. AR status was determined by immunohistochemistry (IHC). Most SDCs were characterized by an apocrine phenotype and AR expression. Cases with a nonapocrine phenotype and AR-negative status were studied by additional IHC and fluorescence in situ hybridization for ETV6 or MYB/NFIB. The diagnosis of SDC was confirmed in 187 of 199 (94%) cases. Variant morphologies were identified in 12 cases: micropapillary (n=6), sarcomatoid (n=3), mucinous (n=2), and basal-like (n=1). AR IHC was performed in 183 cases, of which 179 (97.8%) showed AR expression. On the basis of morphologic appearance and results of additional studies, 12 cases were reclassified as squamous cell carcinoma (SCC) (n=4), epithelial-myoepithelial carcinoma with high-grade transformation (HGT) (n=2), myoepithelial carcinoma (n=2), mammary analogue secretory carcinoma, high grade (ETV6 translocated; n=1), adenoid cystic carcinoma with HGT (n=1), acinic cell carcinoma with HGT (n=1), and adenosquamous carcinoma (n=1). AR-negative SDC is extremely rare, and the majority of such cases are more accurately classified as other entities. HGTs of other salivary carcinomas and squamous cell carcinoma are the most common mimics of SDC. SDCs with variant morphologies still show at least a minor component of conventional apocrine appearance. Thus, apocrine morphology defines SDC.

Update from the 4th Edition of the World Health Organization Classification of Head and Neck Tumours: Tumors of the Salivary Gland

“…Epithelial myoepithelial carcinoma is somewhat unique in that the transformed phenotype may range from myoepithelial to ductal to undifferentiated [52]. Tumors with HGT may mimic salivary duct carcinoma, and in fact, most non-apocrine androgen receptor negative "salivary duct carcinomas" are in fact unrecognized HGT of another tumor type [53].…”

Salivary Duct Carcinoma: An Update on Morphologic Mimics and Diagnostic Use of Androgen Receptor Immunohistochemistry

“…1a). Strong diffuse expression of AR in >95% of SDC is a practical tool in workup of high grade salivary carcinomas [4]. The finding of strong AR expression in SDC was an incidental discovery.…”

“…The follow-up study included additional cases of SDC, all of which were AR-positive [2]. In a recent multi-institutional study, 179 of 183 (97.8%) were AR-positive [4]. Over 85% of SDCs demonstrated easily assessed, unequivocal positive staining with an Allred total score from 6 to 8 (Fig.…”

Histopathological case report of high grade salivary duct carcinoma

“…Development of salivary duct tumors was assessed in view of viral infections (mostly Epstein-Barr virus, cytomegalovirus and SV40) but results are equivocal [1,4]. Whereas involvement of ionizing radiation and increased expression of hormone receptors (ER, PR and AR; androgen receptor) in www.fhc.viamedica.pl salivary tissue is strongly evidenced [5,6]. No association between tobacco use and alcohol consumption was found.…”

“…Therefore, HER-2 status should be evaluated at least in the presence of advanced SDC, and targeted therapy should be considered in the adjuvant setting [13]. During regular course of the disease as well after recommended treatment whole or partial facial nerve paralysis is very often observed, even up to 60% of cases [1,5,7]. Prognosis is relatively poor and most strongly correlates with clinical stage.…”