Consequences of preoperative diagnostic limitations in a rare case of adenoid cystic carcinoma of the breast in a young patient: a case report

Adenoid cystic carcinoma of the breast (ACCB) is a rare triple-negative malignancy typically affecting postmenopausal women. Due to its scarcity, particularly in the adolescent population, standardized treatment guidelines remain undefined. This study reports an exceptional case of ACCB in an 18-year-old female to highlight the diagnostic challenges associated with breast masses in this age group. The patient presented with a painful mass and nipple retraction, classified as BI-RADS 4A. However, based on a clinical presumption of fibroadenoma, she underwent segmental mastectomy without prior biopsy. Histopathology subsequently revealed a high-grade, triple-negative ACCB with involved margins. Consequently, the patient required a completion mastectomy with lymph node dissection and adjuvant chemotherapy. Genetic testing identified a variant of uncertain significance in the PALB2 gene, and the patient remains disease-free five years post-treatment. The results illustrate the risks of omitting preoperative histological assessment. Conclusively, this case underscores the critical necessity of performing core needle biopsies on suspicious lesions in adolescents. Early histological diagnosis is essential to ensure appropriate surgical planning and avoid the treatment escalation caused by incomplete initial interventions.