[Extra-medullary intradural melanotic tumor: apropos of a case of dorsal pigmented neurinoma. Review of the literature].

The authors report a case of pigmented thoracic neuroma (T3) discovered in a 40 year old woman on a routine chest x-ray. This hourglass-shaped extra-dural tumour was investigated by computed tomography, nuclear magnetic resonance imaging and iopamiron myelography. Treatment consisted of complete resection by T2-T3 laminectomy and left T3 foraminotomy. Light and electron microscopy revealed melanin secretion by the Schwann cells. A review of the literature confirms the findings observed in our case in terms of the slow clinical course, the benign nature and the excellent prognosis following complete resection, without the need for any radiotherapy or chemotherapy. The various histogenetic theories of extramedullary intra-dural melanotic tumours are reviewed. The difficulties of the differential diagnosis are discussed.