Primary lymphomatoid granulomatosis in the central nervous system: A report of three cases

Lymphomatoid granulomatosis (LYG) is a rare lymphoproliferative disorder characterized by infiltration of Epstein–Barr virus (EBV)‐positive large atypical B‐cells in an angiocentric fashion in a mixed inflammatory background. The histologic spectrum of LYG ranges from reactive proliferation to diffuse large B‐cell lymphoma according to the number of EBV+ B‐cells. It is known that virtually all patients have pulmonary involvement, whereas primary LYG of the other organs has been rarely reported. Herein, we describe three cases of primary LYG of the central nervous system (CNS) without pulmonary lesions, and this is the first collection to be reported in Korea. All of the cases revealed multifocal enhancing necrotic brain lesions masking as metastatic tumors, infection or vasculitis. These patients were successfully managed by corticosteroids and immunomodulating agents without chemotherapy against malignant lymphoma even in grade 3 LYG. We assume that primary CNS LYG might be less aggressive and more controllable than pulmonary LYG. The clinicopathologic characteristics of the cases with a special regard to the differential diagnosis and clinical courses are discussed in combination with an overview of the literature.