Our case report describes the presence of a leiomyoma in the left-hand thumb of a 69-year-old woman, an extremely uncommon location for such a tumor. Leiomyomas are typically benign tumors that arise from smooth muscle, but their occurrence in the hand is unusual. While leiomyomas are more commonly found in the uterus, they may occasionally develop in the extremities, though this is more frequently observed in the lower limbs. These tumors typically present in patients in their third to fourth decades of life, and they are often not diagnosed until surgery because histological pathology is necessary to confirm the diagnosis.