CNS lymphomatoid granulomatosis with lymph node and bone marrow involvements

Lymphomatoid granulomatosis (LYG) in the CNS is an uncommon lymphoproliferative disease with characteristic angiocentric lymphoreticular proliferative and granulomatous lesions exhibiting low‐grade malignant potential. Here we report a rare case of CNS‐LYG, which disseminated to the lymph node and bone marrow. A 50‐year‐old man was diagnosed with CNS‐LYG based on brain biopsy showing perivascular infiltration of CD3‐positive small T‐lymphocytes without overt nuclear atypism. Eight months after the initial neurological symptoms, inguinal lymph node swelling was found and histopathologically diagnosed as peripheral T‐cell lymphoma. TCRγ‐gene rearrangement study using both paraffin‐embedded specimens of brain and inguinal lymph node demonstrated an identical clonal band. Considering the clinical course, we concluded lymph node involvement of CNS‐LYG, suggesting the malignant potential of CNS‐LYG.