Paget disease of the breast diagnosed during pregnancy: a case report

Abstract

Paget disease of the nipple is a rare manifestation of breast cancer, accounting for approximately 0.5%–5.0% of cases, and occurs predominantly in postmenopausal women. Its presentation in young women is uncommon and, during pregnancy and lactation, is considered exceptional, often being associated with delayed diagnosis due to physiological breast changes and clinical similarity to benign conditions. A 33-year-old pregnant woman presented with bloody nipple discharge and a progressive lesion on the left nipple, initially treated as dermatitis and mastitis. Prior imaging studies did not reveal significant abnormalities Persistent symptoms prompted biopsy of the areola-nipple complex, whose histopathological and immunohistochemical studies confirmed the diagnosis of Paget disease of the nipple with overexpression of human epidermal growth factor receptor 2 (HER2). The patient initially underwent breast-conserving surgical excision; however, due to involved margins and the finding of extensive ductal carcinoma in situ associated with a poorly differentiated invasive focus, a unilateral total mastectomy was performed, with the sentinel lymph node negative for metastasis. Adjuvant treatment was administered in the postpartum period with paclitaxel and trastuzumab, and the patient remained free of recurrence to date. This case highlights the diagnostic challenges of Paget disease of the nipple during the gestational and puerperal period and underscores the importance of early biopsy of persistent lesions of the areola-nipple complex, regardless of seemingly benign radiologic findings, to enable timely diagnosis and improved prognosis.