OANA VIOLA BADULESCU, ROXANA HULTOANA, BOGDAN MIHNEA CIUNTU, ADELINA PAPANCEA, STEFAN OCTAVIAN GEORGESCU THE ROLE OF THE IMMUNOHISTOCHEMICAL EXAMINATION IN THE DIAGNOSIS OF CASTLEMAN'S DISEASE Castleman’s disease is characterized by benign angiolymphoid hyperplasia. There are two clinical forms: the localized form in which one lymph node is affected, often paucisimptomatic, treated by radical surgical excision, without recurrence in most cases, and the multicentric form, characterized by systemic manifestations, polyadenopathy (mediastin, cervical region, abdomen, etc.) , organomegaly (e.g. spleen, liver), with a less favorable prognosis than the localized form. The etiology of the disease remains unknown; recent studies suggest the implication of human herpes virus 8 (HHV-8), especially in multicenter forms. We shall present the case of women, aged 23, with Castleman’s disease with retroperitoneal localization, who was admitted to the surgery clinic due to abdominal pains. The initial abdominal CT raised the suspicion of a hepatic lobus caudatus tumor, but the anatomical-pathological result confirmed the diagnosis of angiofolicular hyperplasia of the lymph nodes. Diagnostic methods, histological forms, treatment and prognosis aspects of Castleman’s disease are described below.