Primary malignant lymphoma of the CNS and polyneuropathy in a patient with necrotizing vasculitis treated with immunosuppression.

A woman, aged 58, who had undergone prolonged treatment with corticosteroids for generalized necrotizing vasculitis, and had received azathioprine (Imurel) for 18 months, 4 years after discontinuing the latter treatment, developed peripheral neuropathy and a rapidly progressing cerebral disorder suggesting a basal meningeal process. CSF cytology suggested malignant lymphoma with meningeal involvement. Immunological studies showed an increase of Null-lymphocytes in the peripheral blood. Autopsy disclosed a primary malignant lymphoma of the CNS with the histological appearance of a multilocular immunoblastoma showing almost ubiquitous meningocerebral involvement. Clinical and postmortem examinations failed to demonstrate any systemic extraneural lymphoproliferative disorder. In addition, there was peripheral polyneuropathy of the axonal type with denervation atrophy of skeletal muscle, but without lymphomatous involvement of the neuromuscular system. The possible relations between primary malignant lymphomas of the CNS and previous immunosuppressive treatment of immunoinflammatory disease are discussed in view of the concept of impaired immunoregulation. The pathogenetic background of peripheral polyneuropathy is unknown.