Melanotic schwannoma of the lumbar spine: a case report and literature review

Schwannomas are benign tumors, usually solitary, encapsulated, slow-growing, which have their origin in differentiated neoplastic Schwann cells with extramedullary intradural usual development related to nerve roots. The melanotic schwannoma is a variant of these tumors whose location in almost one third of cases is on the posterior spinal nerve root, with a nonspecific clinical presentation. Magnetic resonance imaging is the most widely used test for the diagnosis, revealing hyperintense T1-weighted sequences and hypointense T2-weighted sequences. Diagnostic confirmation is obtained by histological and immunohistochemical studies, in which there is intense cytoplasmatic pigmentation. There are two distinct types of melanotic schwannomas: sporadic and psammomatous, the latter related to the called Carney complex, a form of multiple endocrine neoplasm with familiar character. In literature we found few cases of these neoplasms, the largest series consisting of five cases. The objective of this study is to report a rare case of melanotic schwannoma of the lumbar spine of the sporadic type of extramedullary location. We also present a brief review of the literature containing the main characteristics of the tumor, including its different forms, differential diagnoses, data from histological and immunohistochemical studies as well as the currently recommended approach in order to contribute to a better understanding of this neoplasm. Los schwannomas son tumores benignos, generalmente solitarios, encapsulados y de crecimiento lento, que tienen su origen en las células de Schwann neoplásicas diferenciadas con desarrollo habitual intradural extramedular relacionado con las raíces nerviosas. El schwannoma melanótico es una variante de estos tumores cuya localización en casi un tercio de los casos se encuentra en la raíz nerviosa posterior, con presentación clínica no específica. La resonancia magnética es el examen más ampliamente utilizado en el diagnóstico, con hiperintensidad en secuencias T1 e hiposeñal en T2. La confirmación del diagnóstico se obtiene por el estudio histológico e inmunohistoquímico, en el que existe una intensa pigmentación citoplásmica. Hay dos tipos distintos de schwannoma melanótico: el esporádico y el psamomatoso, este último relacionado con el llamado complejo de Carney, una forma de neoplasia endocrina múltiple de carácter familiar. En la literatura encontramos pocos casos de estos tumores, la serie más grande consta de cinco casos. El