The current histological criteria for the diagnosis of lymphomatoid granulomatosis (LYG) are reviewed and summarized. The majority of patients present with multiple bilateral nodules involving the lung. Key histologic features necessary for the diagnosis include a mixed mononuclear cell infiltrate that shows vascular infiltration, appreciable numbers of T-cells, and variable numbers of CD20-positive B cells that show positivity for EBER by in situ hybridization.