Castleman disease. A rare clinical case of retroperitoneal tumor localization in an elderly patient

Castleman disease is an extremely rare benign disease of the lymphatic system with an estimated incidence of 1–9 cases per 1,000,000. Its etiology remains unknown; interleukin 6 (IL-6) plays an important role in pathogenesis. Castleman disease has two clinical forms: localized (up to 90 % of cases) with a favorable prognosis, treated predominantly by surgical method; generalized (up to 10 % of cases) with less favorable prognosis, treated by pharmacological therapy. The diagnosis is rarely established at the preoperative stage.The aim. To present a clinical case of diagnosis and treatment of Castleman tumor of a rare topical localization.Results. A 66-year-old patient was admitted at the Abdominal Oncology Department of the G.E. Ostroverkhov Kursk Oncology Scientific and Clinical Center.Diagnosis: Retroperitoneal mass on the right found at the preventive examination; no peripheral lymphadenopathy was detected on ultrasound and computed tomography (CT). After the examination, a preliminary diagnosis was made: Gastrointestinal stromal tumor (GIST) of the small intestine mesentery.  Based on the results of the case conference, the decision was taken to perform a surgery – laparoscopic removal of the tumor under endotracheal anesthesia. For surgical approach, a fan-shaped arrangement of ports was chosen. The surgery had no complications. Intraoperative blood loss was 50.0 ml. The total operating time was 98 minutes.According to the results of the histological study, the following diagnosis was made: Castleman disease, unicentric form, hyaline-vascular variant. En bloc surgery is the standard method for the treatment of localized forms of the Castleman disease. In all cases, long-term follow-up shows a long relapse-free period in almost all patients.During follow-up examinations (ultrasound of the abdominal cavity and retroperitoneal space, CT of the abdominal cavity with contrast enhancement, CT of the chest), no disease recurrence was detected during the year of observation.Castleman disease is a rare non-clonal lymphoproliferative disease of unknown etiology. A rare case of its retroperitoneal localization indicates that in cases with an uncertain nature of the peritoneal mass, Castleman disease should be included in the differential diagnostic search.