Sinonasal non-intestinal-type adenocarcinoma (non-ITAC) is a rare, morphologically diverse neoplasm of the head and neck.\nSquamoid morular metaplasia has recently been reported as an occasional finding in non-ITAC. Interestingly, these squamoid\nmorules often show aberrant expression of CDX2 as well as nuclear expression of ... catenin, similar to other tumors that show this\ntype of metaplasia, but the underlying mechanism responsible for this finding is not completely understood.We present two cases\nof low-grade non-ITAC with squamoid morules coexpressing CDX2 and nuclear ... catenin by immunohistochemistry, both of\nwhich were found to harbor a mutation in CTNNB1, the gene encoding ... catenin. This finding provides support that an alteration\nin the ... catenin pathway, including mutations in the ... catenin gene itself, is responsible for this recently described morphologic\nphenomenon in non-ITAC.
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