An atypical groin mass in a middle-aged woman – inguinal leiomyoma as a rare clinical entity

Abstract

Introduction Leiomyomas are benign smooth muscle tumors that rarely occur outside the uterus. Inguinal canal leiomyomas are particularly uncommon and may resemble hernias, endometriosis, lymphadenopathy, or other soft tissue lesions, making preoperative diagnosis difficult.

Case outline We report the case of a 47-year-old woman with a painless right inguinal mass, first noticed approximately 1.5 years before surgery and progressively enlarged without associated systemic symptoms. Examination revealed a mobile, well-defined, non-tender lesion. Ultrasound showed a heterogeneous, predominantly hypoechoic, vascular mass. Computed tomography demonstrated a hypodense lesion with heterogeneous enhancement and preserved surrounding fat planes. Magnetic resonance imaging revealed a well-circumscribed, partially cystic mass without infiltration or fatty or hemorrhagic components. Its proximity to the round ligament and arterial supply from a branch of the inferior epigastric artery raised the possibility of leiomyoma, endometriosis, or another benign soft tissue tumor. Due to progressive growth and uncertain etiology, the mass was surgically removed in late 2024. Gross examination showed an encapsulated, whitish, elastic lesion. Histology demonstrated a mesenchymal proliferation without atypia or necrosis. Positive staining for α-smooth muscle actin, caldesmon, desmin, estrogen receptors, and progesterone receptors, together with a Ki-67 index below 1%, established the diagnosis of leiomyoma. Two postoperative abdominal ultrasound examinations, including both inguinal regions, showed no evidence of local recurrence. The patient remains asymptomatic.

Conclusion Inguinal canal leiomyoma should be considered in the differential diagnosis of a slowly growing groin mass. Imaging defines its extent and relationship to adjacent structures, while histopathology and immunohistochemistry establish the definitive diagnosis and guide treatment.

Keywords: leiomyoma; inguinal canal; groin mass; differential diagnosis; case report