SMARCB1-deficient sinonasal adenocarcinoma: a rare variant of SWI/SNF-deficient malignancy often misclassified as high-grade non-intestinal-type sinonasal adenocarcinoma or myoepithelial carcinoma

AbstractSMARCB1-deficient sinonasal adenocarcinoma is a rare variant of SWI/SNF-deficient malignancies with SMARCB1 loss and adenocarcinoma features. More than 200 high-grade epithelial sinonasal malignancies were retrieved. A total of 14 cases exhibited complete SMARCB1 (INI1) loss and glandular differentiation. SMARCA2 and SMARCA4 were normal, except for one case with a loss of SMARCA2. Next-generation sequencing (NGS) and/or fluorescence in situ hybridization (FISH) revealed an alteration in theSMARCB1 gene in 9/13 cases, while 2/13 were negative. Two tumors harboredSMARCB1 mutations in c.157C  >  T p.(Arg53Ter) and c.842G >  A p.(Trp281Ter). One harboredARID1B mutations in c.1469G  >  A p.(Trp490Ter) andMGA c.3724C  >  T p.(Arg1242Ter). Seven tumors had aSMARCB1 deletion. One carried anESR1 mutation inc.644-2A >  T, and another carried aPOLE mutation in c.352_374del p.(Ser118GlyfsTer78). One case had aPAX3 mutation in c.44del p.(Gly15AlafsTer95). Histomorphology of SMARCB1-deficient adenocarcinoma was oncocytoid/rhabdoid and glandular, solid, or trabecular in 9/14 cases. Two had basaloid/blue cytoplasm and one showed focal signet ring cells. Yolk sac tumor-like differentiation with Schiller-Duval-like bodies was seen in 6/14 cases, with 2 cases showing exclusively reticular-microcystic yolk sac pattern. Follow-up of a maximum of 26  months (median 10 months) was available for 8/14 patients. Distant metastasis to the lung, liver, medias...
Source: Virchows Archiv - Category: Pathology Source Type: research