Solitary pelvic osteochondroma causing L5 nerve root compression

Osteochondroma is the most common benign bone tumor, accounting for more than one-third of all benign bone tumors. It usually develops at the metaphysis of the long bones, especially the distal femur and proximal tibia. Approximately 40% of osteochondromas are found around the knee. Osteochondroma commonly presents as a painless mass and is incidentally identified via plain radiographs. Thus, surgical excision is not routinely recommended unless the tumor causes clinical symptoms or cosmetic distress. Osteochondroma located in the pelvis is unusual. Spinal nerve root compressions due to pelvic osteochondroma are also rarely reported. We assessed the solitary pelvic osteochondroma of a 33-year-old man mimicking spinal disease. An exostotic bony projection composed of dense calcification of the cartilaginous cap arose from the iliac crest, which was located just lateral to the right sacroiliac joint in the paravertebral area, L5 level. Magnetic resonance imaging showed an irregular, exophytic outgrowing calcified mass with cartilage cap and exostotic mass compressed to the proximal part of the right L5 nerve root lateral to the nerve root foramen. The L5 nerve root was focally compressed and thinned.En bloc excision, the treatment of choice of symptomatic osteochondroma, was performed. The patient had complete resolution of symptoms postoperatively, and other neurologic symptoms may be expected to improve over time.