METHODS A case report. OBJECTIVE Giant cell tumors are rare primary bone tumors. Generally, these tumors are expanding osteolytic lesions, but soft tissue giant cell tumors can occur. This is a case report of an unusual incidence of a giant cell tumor within the spinal sacral canal, in which there was no involvement of the surrounding bone or ligament structures and that was signaled by radicular pain. The pathologic course of the tumor is described. BACKGROUND A 24-year-old woman had monoradicular pain in the right leg in the region of S2. Neuroradiologic examination showed a mass within the sacral spinal canal compromising the right S2 root, with no sign of bone involvement. METHODS A sacral laminectomy was performed. A tumor was located entirely intraspinally and extradurally and was removed completely. A giant cell tumor was identified in histologic examination. RESULTS The patient recovered completely. No local regrowth or metastasis occurred during a 20-month follow-up. CONCLUSIONS The treatment of choice in giant cell tumors is complete surgical resection. Radiotherapy is recommended in cases of subtotal resection. Careful follow-up is warranted, because recurrence and metastasis are not uncommon.