Mammary-like adenocarcinoma of the vulva: a rare case report with next generation sequencing.

Vulvar adenocarcinomas are rare tumors, representing approximately 5% of vulvar cancers. Mammary-like adenocarcinomas of the vulva (MLAV) are extremely rare, and their molecular features are poorly described in the scientific literature. We report a case of an 88-year-old woman affected by MLAV with comedo-like features, with a detailed description of the pathological, immunohistochemical and molecular features. Immunohistochemistry (IHC) showed strong staining for cytokeratin 7, GATA3, androgen receptor, GCFPD15, and weak staining for mammaglobin; no staining for Her-2 was found. The proliferation index (Ki-67) was 15%. Molecular testing detected a pathogenic mutation of the AKT1 gene, a likely pathogenic frameshift insertion of the JAK1 gene, and two likely pathogenic frameshift deletions of the KMT2C gene; in addition, two variants of unknown significance (VUS) involving the ARID1A and OR2T4 genes were detected. Finally, two CNVs of the BRCA1 gene were identified.