Myxoma of the round ligament mimicking femoral hernia: a diagnostic surprise in the operating room.

Introduction: Groin swellings in adult women are most commonly attributed to inguinal or femoral hernias. However, rare neoplasms arising from the round ligament of the uterus may present with similar clinical features, posing significant diagnostic challenges. Myxomas are benign mesenchymal tumors characterized by an abundant myxoid stroma, but their occurrence in the round ligament is exceedingly rare. Case presentation: A 30-year-old woman presented with a 1-year history of a progressive, painless swelling in the left groin. Clinical examination revealed a soft, reducible mass located below the inguinal ligament, leading to a preoperative diagnosis of uncomplicated femoral hernia. No imaging was performed. Surgical exploration via an inguinal approach revealed no femoral or inguinal hernia. Instead, a well-encapsulated, gelatinous mass measuring 5 cm was identified, arising from the round ligament. Complete excision of the mass with the involved segment of the ligament was performed. Histopathological examination demonstrated abundant myxoid stroma containing scattered stellate and spindle cells without atypia or mitoses, consistent with a benign myxoma of the round ligament. The postoperative course was uneventful, and no recurrence was observed at the 3-month follow-up. Discussion: This case highlights the diagnostic complexity of groin swellings in women and underscores the importance of maintaining a broad differential diagnosis. When intraoperative findings deviate from expectations, the surgeon must be prepared to adapt the operative plan and ensure histopathologic confirmation. Conclusion: Round ligament myxoma is an exceptional clinical entity that can mimic a femoral hernia. Awareness of such rare pathologies aids appropriate perioperative management and accurate diagnosis.