Abstract
BACKGROUND: The accessory breast is composed of residual glandular mammary tissue that persists after normal embryonic development. The entity is so rare that it is easily neglected in the diagnosis of disease. CASE PRESENTATION: We report a 24-year-old virgin Persian woman with a left-sided vulvar mass and no pain or discomfort until shortly before her presentation at our department. Ectopic breast tissue in the vulva was diagnosed. We performed wide local resection of the lesion. Pathological investigation of the lesion confirmed the presence of ectopic breast tissue with secretory changes. She had no specific developmental abnormalities and had no relevant family history. She was followed up for 10 months and had recovered fully by this time. CONCLUSION: Accessory breast tissue should be considered as a diagnosis when a mass is seen along the embryonic milk line, especially if the clinical findings reveal changes in the mass accompanied by changes in sex hormones.