Giant fibroadenoma mimicking phyllodes tumor: diagnostic pitfalls and surgical management in an adult patient – a case report and review of the literature

Introduction: Giant fibroadenoma is a rare fibroepithelial neoplasm, particularly in adult women. Its rapid expansion creates a diagnostic dilemma, as it often obscures the distinction between phyllodes tumors and malignancies on clinical and radiographic grounds. Case presentation: A 36-year-old woman presented with recent-onset breast asymmetry. Clinical examination revealed a large, firm, mobile mass in the left breast without skin changes or lymphadenopathy. Ultrasonography demonstrated a well-defined hypoechoic mass (117 × 103 × 60 mm), classified as Breast Imaging-Reporting and Data System 4A. Core needle biopsy (CNB) showed benign stromal fibrosis with degenerative changes; however, radiologic–pathologic discordance was noted. Complete surgical excision was performed. Histopathology confirmed a benign giant fibroadenoma. Postoperative recovery was uneventful, with an excellent cosmetic outcome. Conclusion: This case highlights the diagnostic limitations of CNB in large fibroepithelial lesions and underscores the importance of clinicoradiologic–pathologic correlation. Surgical excision provides a definitive diagnosis and favorable cosmetic results.