Extra-abdominal Desmoid Tumor Mimicking Cervical Spine Schwannoma

Extra-abdominal desmoid tumors (DTs) are rare tumors of apparent fibroblastic origin with unpredictable clinical behavior. Though histologically benign and slow growing, DTs can be proliferative, aggressive tumors, invading the surrounding areas. DTs located extra-abdominally are most commonly found in the extremities or proximal structures like the shoulders, chest wall, and neck. Spinal involvement is very rare. Here, we describe a case where an extra-abdominal DT mimicked a schwannoma in the posterior cervical spine. A 67-year-old female patient presented with acute neck and bilateral shoulder pain. After attempting conservative treatments with no symptomatic relief, a magnetic resonance imaging of the cervical spine was obtained, showing a paraspinal mass in the posterior elements from C2 to C4. The computed tomography guided needle biopsy showed rare spindle cells, suggestive of a spindle cell neoplasm, and complete surgical resection was performed. The pathology report was consistent with fibromatosis, leading to a final diagnosis of the extra-abdominal desmoid. This case demonstrates a rare presentation of an unusual tumor that often manifests with nonspecific symptoms or no symptoms at all.