Lymphoplasmacytic/lymphoplasmacytoid immunocytoma with a high content of epithelioid cells. Histologic and immunohistochemical findings.

Fifty-four lymph node biopsy specimens from 36 patients with lymphoplasmacytic/lymphoplasmacytoid immunocytoma with a high content of epithelioid cells (LPICep) were studied by light microscopy using conventional histologic and immunohistochemical techniques. Three other patients with extranodal involvement only were also included in the study. Of a total of 39 patients, 31 had the polymorphic subtype, six the lymphoplasmacytoid subtype, and two the lymphoplasmacytic subtype. Cellular composition and histologic structure are described in detail as a basis for discriminating LPICep from similar lymphomas with a high content of epithelioid cells, especially from lymphoepithelioid cell lymphoma (Lennert's lymphoma), angioimmunoblastic peripheral T-cell lymphoma with a high content of epithelioid cells, and Hodgkin's disease, mixed cellularity type with a high content of epithelioid cells. In 10 patients (26%) LPICep developed into a high-grade malignant lymphoma of B-immunoblastic type. Forty-seven biopsy specimens were studied with the peroxidase-antiperoxidase method to detect intracytoplasmic immunoglobulin. Plasma cells and plasma cell precursors revealed a monotypic immunoglobulin pattern in all specimens. In 25 biopsy specimens in which giant cells resembling Sternberg-Reed and Hodgkin's cells were found, these cells were CD15 negative. A comparison of the main clinical and laboratory data in these four lymphomas with a high content of epithelioid cells revealed both similarities and differences.