Symptomatic Plantar Osteochondroma of the Third Metatarsal With Toe Flexion Deformity: A Case Report

Although osteochondroma is the most common benign bone tumor, it rarely affects the foot, particularly the plantar aspect of the metatarsals. Plantar lesions are clinically significant due to their involvement in weight-bearing and potential to cause pain and deformity. We report the case of an 18-year-old male presenting with a painful plantar mass of the left foot arising from the distal third metatarsal. The lesion had been present for three years with rapid growth over the preceding four months, resulting in plantar pain, toe flexion deformity, and functional limitation. Clinical examination revealed a well-circumscribed, hard mass measuring approximately 2 cm. Imaging studies demonstrated a calcified exostosis originating from the plantar surface of the third metatarsal. The lesion was surgically excised through a plantar approach. Histopathological examination confirmed the diagnosis of osteochondroma. At the one-year follow-up, the patient was pain-free, with no evidence of recurrence and restoration of normal toe motion. This case highlights a rare plantar localization of a third metatarsal osteochondroma and emphasizes the importance of recognizing atypical sites to ensure timely surgical management and optimal functional outcomes.