Non-Hodgkin's lymphoma of the brain after Hodgkin's disease. An immunohistochemical study. Non-Hodgkin's lymphoma (NHL) of the central nervous system (CNS) is a rarely reported complication of Hodgkin's disease (HD). Two patients with NHL of the brain after HD were studied by histologic and immunohistochemical methods. Both patients were in the second decade, had been treated with radiation and chemotherapy, had experienced a relapse of HD before development of NHL, had no evidence of HD at the time of diagnosis of NHL, and died within 1 year of diagnosis. Both brain neoplasms were large cell immunoblastic lymphomas of B-cell lineage. Patients with HD appear to be at increased risk for NHL of the CNS, which may have a poor prognosis. 