Lymphomatoid granulomatosis: insights gained over 4 decades.

Lymphomatoid granulomatosis is a rare lymphoproliferative disease involving predominantly the lung, and there is uncertainty about its relationship to lymphoma. It affects mainly middle-aged adults, although there is a wide age range, and men are affected almost twice as often as women. Multiple nodular, usually bilateral, infiltrates are seen radiographically, and extrapulmonary involvement, especially of skin and nervous system, occurs in more than one third of the patients. Mortality rates are high, and treatment modes are not well established. Morphologically, there is a nodular polymorphous mononuclear cell infiltrate with prominent vascular infiltration and often necrosis. Varying numbers of large, often atypical, CD20-positive B-lymphocytes are present within a background containing numerous CD3-positive small T lymphocytes and scattered admixed plasma cells and histiocytes. Evidence of Epstein-Barr virus infection can be shown in most cases by in-situ hybridization for Epstein-Barr virus RNA. The infiltrate is graded as 1 to 3 based on the proportion of large B cells. Morphologically, there is overlap in grades 2 and 3 with variants of large B-cell lymphoma, and many such cases show evidence of monoclonality by polymerase chain reaction. It is suggested that lymphoma (T-cell rich large B-cell or diffuse large B-cell) be diagnosed in addition to lymphomatoid granulomatosis in grades 2 and 3 to appropriately communicate the nature of the disease to clinicians.