Localized retroperitoneal mass suspected malignancy: A rare case of unicentric Castleman's disease.

Key Clinical Message: Castleman's Disease should be considered in the differential diagnosis of retroperitoneal masses, especially in equivocal cases. Clinician should not presume all cases of retroperitoneal masses as a malignancy.

Abstract: Castleman's Disease is a heterogeneous group of lymphoproliferative disorders, that can develop in lymph nodes or in extranodal sites. It has three distinct histological subtypes; hyaline vascular, plasma cell or mixed. It can be unicentric or multicentric, and sometimes oligocentric or regional. In this article, we report a case of a 30-year-old male who presented with a palpable left lumbar mass, clinically suspected as sarcoma vs GIST, which was surgically excised and pathologically examined revealing a rare condition of intra-abdominal unicentric Castleman's Disease with good prognosis. Castleman's Disease should be considered in the differential diagnosis of retroperitoneal masses, especially in equivocal cases.