Challenging Diagnosis of a Solitary Retroperitoneal Mass: A Case Report of Castleman's Disease and Review of the Literature.

Castleman's disease (CD) is an uncommon type of lymphoproliferative disorder. Its etiology and prevalence are unclear. The retroperitoneum is a very rare site for presentation of the unicentric variant, where it mimics malignant tumors. A 59-year-old man is referred to the urology outpatient clinic for the study of microhematuria found in a routine analysis. CT scan of the abdomen identified a solid, circumscribed mass, measuring 28 × 30 × 31 mm in the left para-aortic zone, with homogeneous contrast enhancement. Excisional surgery and regional lymphadenectomy were performed via laparoscopy. Postoperative course concurred without incidences. Histological diagnosis confirmed unicentric CD, hyaline-vascular type. CD is a rare entity, and the unicentric type presents as an asymptomatic mass. Retroperitoneum is a rare localization, where initial imaging diagnosis is unclear and surgical resection is the preferred treatment.