Scaphoid Cortical Desmoid in a Snowboarder With Persistent Wrist Pain

A 28-year-old man presented to our clinic with persistent left wrist pain. Three months earlier, he had fallen on an outstretched hand while snowboarding. Initial radiographs showed no fractures or dislocations; however, magnetic resonance imaging revealed evidence of a dorsal projection from the scaphoid waist. There was no evidence of a scaphoid wrist fracture, scapholunate ligament disruption, or injury. The final diagnosis was avulsive cortical irregularity or cortical desmoid, which pertains to new bone formation at sites of muscle insertion. The literature has identified cases found in the deltoid, latissimus dorsi, adductor magnus muscles, and gastrocnemius insertion; however, it has never been reported in the scaphoid region. The proposed mechanism, in this case, is the repetitive pull on the radioscaphoid ligament. Avulsive cortical irregularities are benign conditions that mimic malignant conditions radiologically and microscopically. It is therefore important not to mistake this lesion for more worrisome lesions such as osteosarcoma or fibrosarcoma to avoid unnecessary procedures. In the incidental setting, no further imaging is necessary. If the patient presents with pain, atypical radiographical findings, or a suspicion of malignancy, a magnetic resonance image can provide valuable information and confirmation of diagnosis.