Novel case of anastomosing hemangioma of the extradural space: illustrative case.

backgroundAnastomosing hemangiomas are benign vascular neoplasms occurring mainly in the genitourinary tract and paraspinal soft tissues. There have been no reported cases of anastomosing hemangiomas occurring in the spinal epidural space; therefore, their clinical and radiological presentations remain unclear. OBSERVATIONS: A 55-year-old man presented with progressive back pain and motor and sensory disturbances in both lower extremities. Magnetic resonance imaging (MRI) revealed an extradural lesion at the T4-6 level that extended into the extraspinal region through the left T5-6 intervertebral foramen. Axial MRI revealed that the tumor encircled the spinal cord, with sharp horn-like ends in the intraspinal canal. The patient underwent complete tumor resection with T4-6 laminectomy and left T5-6 foraminotomy. The histopathological diagnosis was an anastomo-sing hemangioma exhibiting anastomosing proliferation of capillary vessels with hobnailed endothelial cells. His symptoms improved, and tumor control was achieved 4 months after surgery without adjuvant therapy. LESSONS: Although rare, anastomosing hemangiomas can occur in the spinal epidural space. Radiologically, the tumors show horn-like projections encircling the spinal cord, which can be diagnostic cues. Anastomosing hemangiomas should be included in the differential diagnosis of spinal epidural tumors, especially when characteristic horn-like projections are present. https://thejns.org/doi/10.3171/CASE24265.