Multicentric reticulohistiocytosis and urologic carcinomas: a possible paraneoplastic association.

Multicentric reticulohistiocytosis (MR) is a rare non-Langerhans histiocytosis that is characterized by cutaneous nodules and severe destructive arthritis. Although 25-30% of reported cases have been associated with internal malignancies, the pathophysiology of MR is unknown. Herein, we report two cases of MR that were associated with urologic neoplasms. Because the tumor suppressor gene p53 may play a role in the biology of other histiocytoses, we investigated its p53 immunoexpression in these two cases. Both cases were positive immunohistochemically, but it remains to be seen whether this finding is truly important in the pathogenesis of MR associated with underlying visceral neoplasms.