Primary Breast Adenocarcinoma in Ectopic Breast Tissue in the Vulva: A Case Report

Abstract Background Primary breast adenocarcinoma arising in ectopic breast tissue within the vulva is an exceedingly rare occurrence, posing significant diagnostic challenges due to its unusual presentation. Differentiating it from other vulvar neoplasms is crucial for prompt and appropriate management. Case Description We present the case of a 55-year-old female with a history of negative medical and family history, presenting with an atypical vulvar lesion with extensive bone metastasis. Even though normal findings were obtained on mammogram and breast ultrasound, biopsy revealed undifferentiated carcinoma. Further immunohistochemical analysis supported a diagnosis of mammary carcinoma originating from malignant accessory breast tissue. Treatment involved paclitaxel and carboplatin chemotherapy along with zoledronic acid infusions and pelvic bone radiotherapy, which resulted in an initial complete response. However, a subsequent vulvar lesion recurrence necessitated hormonal therapy, leading to another complete response. Conclusion This case highlights the diagnostic complexity and therapeutic challenges associated with primary breast adenocarcinoma in vulvar ectopic breast tissue. Comparison with similar cases underscores the importance of meticulous evaluation, precise immunohistochemistry, and interdisciplinary collaboration for accurate diagnosis and tailored treatment.