Adenocarcinoma of Mammary Gland Type of the Vulva.
Gauri Nakra, Aishwarya Sharma, Rasheeda Mohamedali et al.
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Case in brief
A 38-year-old woman presented with an ulcerated lesion of the left labia majora. The tumor was diagnosed as adenocarcinoma of mammary gland type of the vulva. Immunohistochemistry showed expression of keratin 7, p16, GATA3, TRPS1, HER2, and androgen receptor, with no expression of p63, p40, estrogen receptor, or progesterone receptor. Sequencing identified pathogenic PIK3CA and TP53 variants; copy-number analysis showed ERBB2 amplification and gains in CDKN2A and CDK4. The abstract does not report treatment or clinical outcome.
What made this case unusual
The vulvar tumor had a mammary-type immunophenotype and molecular findings, including ERBB2 amplification, in a malignancy believed to arise from mammary-like vulvar glands.
Diagnostic / clinical pearl
For an ulcerated vulvar lesion with glandular malignancy, consider mammary gland-type adenocarcinoma and use morphology with immunohistochemical and molecular findings to distinguish it from mimics.
Why it matters
The authors note that distinguishing this rare tumor from morphological mimics can inform management; treatment approaches are typically based on primary breast cancer protocols.