Lipomas are the most common benign mesenchymal tumors, often localized to the neck, trunk, and extremities. However, their occurrence in the hand, particularly involving commissures, remains extremely rare. We report the case of a 61-year-old woman who presented with a massive, asymptomatic lipoma occupying the thenar space and extending into adjacent interosseous spaces, evolving over more than a decade. Despite the significant size of the tumor, no neurological deficits were observed.

MRI imaging revealed a well-circumscribed, T1- and T2-hyperintense mass infiltrating the palm and closely associated with flexor tendons, without evidence of neurovascular invasion. Complete surgical excision was performed under locoregional anesthesia with meticulous dissection, preserving all critical structures. Postoperative recovery was uneventful, with restoration of full hand and thumb function within days. Histopathological analysis confirmed a benign lipomatous lesion.

This case highlights the importance of MRI in the preoperative evaluation to delineate tumor extent, assess potential malignant features, and plan a safe surgical approach. Although rare, giant hand lipomas must be included in the differential diagnosis of palmar masses to avoid misdiagnosis and ensure appropriate management. Surgical excision remains the treatment of choice, particularly for lesions exceeding 5 cm due to potential sarcomatous transformation. Early recognition and intervention can prevent functional impairment and preserve hand biomechanics.

Keywords: Lipoma, Hand, Commissure, Surgery, MRI