Asian Journal of Case Reports in Surgery

Background: Adenomyoepithelioma is a rare biphasic breast tumour with diagnostic and management challenges due to its variable clinical, radiological, and pathological features.

AIM: To highlight the diagnostic challenge of adenomyoepithelioma of the breast, a rare biphasic tumour that can clinically and radiologically mimic common benign lesions such as fibroadenoma.

Presentation of Case: A 24-year-old female presented with a one-year history of a progressively enlarging mass in the left breast. Clinical assessment and radiological findings indicated a benign lesion, most likely a fibroadenoma. Fine-needle aspiration cytology likewise supported a diagnosis of fibroadenoma. The patient subsequently underwent a lumpectomy. Histopathological evaluation demonstrated a well-circumscribed biphasic tumour comprising proliferating epithelial and myoepithelial components, consistent with benign adenomyoepithelioma. Surgical margins were confirmed to be tumour-free. The postoperative recovery was uncomplicated, and the patient remains asymptomatic with no clinical or radiological evidence of recurrence during follow-up.

Discussion: Adenomyoepithelioma is a rare breast tumour characterized by dual epithelial and myoepithelial proliferation. Its clinical and radiological features are nonspecific, often leading to misdiagnosis as fibroadenoma or other benign lesions. Cytology may not reliably distinguish AME due to overlapping features. Histopathology remains the gold standard for diagnosis. Although typically benign, AME carries a risk of local recurrence and rare malignant transformation, particularly in cases with incomplete excision.

Conclusion: Adenomyoepithelioma should be considered in the differential diagnosis of benign-appearing breast lumps. Accurate diagnosis relies on histopathological evaluation. Complete surgical excision with clear margins is essential to prevent recurrence and ensure favourable outcomes.