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 <i>AKT1</i> gene, a likely pathogenic frameshift insertion of the <i>JAK1</i> gene, and two likely pathogenic frameshift deletions of the <i>KMT2C</i> gene; in addition, two variants of unknown significance (VUS) involving the <i>ARID1A</i> and <i>OR2T4</i> genes were detected. Finally, two CNVs of the <i>BRCA1</i> gene were identified.