An immunological study of germinal centres in four ophthalmic immunocytomas.

Four ophthalmic lymphoplasmacytic/lymphoplasmacytoid (LP) immunocytomas with germinal centres were reviewed histologically and studied immunologically by means of the peroxidase-antiperoxidase (PAP) method. In two cases a histological diagnosis of LP immunocytoma was made, while in the other two cases a non-Hodgkin's lymphoma could not be histologically differentiated with certainty from a pseudolymphoma or reactive process. Immunological analysis confirmed the diagnosis in the former two cases and led in one of the latter also to a diagnosis of LP immunocytoma. In the fourth case the development of LP immunocytoma out of a pseudolymphoma could be demonstrated. In the four LP immunocytomas the germinal centres showed a monoclonal pattern of immunoglobulin in one case, a polyclonal pattern in one case and a negative reaction in two cases. The role of germinal centres in relation to the development of LP immunocytoma is discussed.