Adenomyoepithelioma of the breast with recurrent misdiagnoses: A case report highlighting diagnostic challenges and the role of immunohistochemistry

Adenomyoepithelioma (AME) of the breast is a rare biphasic tumor frequently misdiagnosed due to morphological overlaps with common breast lesions. Accurate diagnosis requires immunohistochemical confirmation. A 28-year-old woman presented in 2023 with recurrent left breast lumps over several months. Initial excisional biopsy was reported as benign. On recurrence, core needle biopsy suggested invasive ductal carcinoma, prompting mastectomy. Histopathology revealed AME, confirmed by immunohistochemistry (cytokeratin/EMA-positive epithelial cells; p63/SMA/S100-positive myoepithelial cells). Concurrently, a separate lesion proved to be a malignant phyllodes tumor on wide local excision. The patient defaulted from adjuvant therapy and re-presented six months later with a massive fungating mass, requiring debulking surgery and radiotherapy. Coexistence with a malignant phyllodes tumor further complicates management.