An Unusual Presentation of Costal Intraspinal Osteochondroma Causing Compressive Myelopathy in a Patient With Hereditary Multiple Exostoses: A Case Report and Literature Review

A 22-year-old man presented to us with back pain for four months, inability to walk, and weakness in both lower limbs. Clinical examination revealed multiple swellings in the body, motor weakness, paresthesia, and upper motor neuron signs. Both magnetic resonance imaging (MRI) and computed tomography (CT) revealed an abnormal bone mass protruding into the spinal canal from the posterior aspect of the ninth rib through the D9-D10 neural foramen. After routine preoperative evaluation, the lesion was removed en masse along with the rib to which it was attached. Osteochondroma was the histological diagnosis. After the procedure, the patient's symptoms subsided, and he could return to his daily activities. From this case, we recommend performing whole spine MRI screening for all patients with hereditary multiple exostoses to diagnose intraspinal lesions that need to be addressed early to have a good postoperative outcome.