ALK-positive anaplastic large cell lymphoma presenting as intradural spinal mass: first reported case and review of literature.

Anaplastic large cell lymphoma (ALCL) is characterized by large anaplastic cells of T-cell or null-cell phenotype expressing CD30 (Ki-1 antigen). In most cases this neoplasm expresses the anaplastic lymphoma kinase (ALK), a chimeric protein resulting from the t(2;5)(p23;q35) translocation. ALK-positive anaplastic large cell lymphoma is most frequent in the first three decades of life and shows a male predominance, involving both nodal and extranodal sites, but rarely the CNS. We report a 21-year-old patient with a previous history of nodal ALK-positive ALCL, lymphohistiocytic subtype, who was admitted for recent occurrence of left-sided anesthesia with pain and progressive motor weakness of both legs. An MRI of the spine documented an intradural extramedullary mass dislocating the thoracic cord, suggesting a meningioma and the patient underwent surgical decompression. Histological examination revealed a lymphoproliferative neoplasm with morphology and immunophenotype of ALK-positive anaplastic large cell lymphoma. After surgery, all preoperative symptoms disappeared. To our knowledge, no cases of ALCL presenting as secondary localization with an intradural extramedullary spinal mass have been reported in the literature.