Lymphomatoid papulosis is a disorder characterized by recurrent skin lesions with histological features suggestive of malignant lymphoma. In most cases the cutaneous lesions heal spontaneously but the course of the disease is long-lasting and an evolution into a Hodgkin's disease and non-Hodgkin lymphomas may be seen. We report herein the clinical, pathological and immunohistochemical study of three patients having a long-standing lymphomatoid papulosis, which turned into Hodgkin's disease, mycosis fungoides and nodular paragranuloma, respectively. Immunohistochemical analysis showed that the immunophenotype of atypical cells in lymphomatoid papulosis was similar to that observed in Reed-Sternberg cells in Hodgkin's disease and the neoplastic cells of mycosis fungoides. However, the immunohistochemical profile of cells in lymphomatoid papulosis differed from those observed in cells of nodular paragranuloma, developed by one of the three patients. The relationship between lymphomatoid papulosis and malignant lymphomas associated to lymphomatoid papulosis is discussed. The results show that no definitive criteria can be infered from an immunohistochemical study in lymphomatoid papulosis, in predicting the clinical evolution of the disease.