A case of disseminated recurrent retroperitoneal plasmacytoma with left obstructive hydronephrosis.

Retroperitoneal extramedullary plasmacytoma (EMP) is a rare condition that often poses a diagnostic challenge. This is mainly due to its unusual location and non-specific symptoms especially in its early stages. Retroperitoneal plasmacytoma with renal involvement is an extremely rare entity and to date, less than 25 cases have been reported in the literature. We describe a case of a 65-year-old woman with primary retroperitoneal plasmacytoma, confirmed by ultrasound-guided biopsy and histopathological examination, with unilateral left obstructive hydronephrosis and metastasis to the lungs. Our patient was started on chemotherapy to which she did not respond. Subsequently, she resorted to palliative measures. Our case highlights key aspects of clinical presentation, diagnosis and treatment options available for management of retroperitoneal plasmacytoma.