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

Abstract

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.

Keywords: MLAV; mammary-like adenocarcinoma; next generation sequencing; vulvar cancer.

Figure 1.

Morphological features of the tumor: (a) a mixed pattern with solid and cystic areas is evident, hematoxylin and eosin (H&E), magnification 10x; (b) cystic comedo-like areas, H&E, magnification 20x; (c) the same features seen in a are seen here in higher magnification, H&E, magnification 20x; (d) in the solid areas of the tumor cells are organized mainly in cribriform patterns, H&E, 10x.

Figure 2.

Main immunohistochemical features of the tumor: strong staining for androgen receptors (a), GATA 3 (b) and cytokeratin 7 (c); week staining for mammaglobin (d).

Figure 3.

Details of the genetic alterations found through next generation molecular testing.