Radiologic features of Castleman's disease involving the renal sinus: A case report and review of the literature.

Background: We present a rare case of plasma cell type of Castleman's disease (CD) involving only the right renal sinus in a 65-year-old woman with a duplex collecting system (DCS).

Case Summary: The patient presented with a right renal sinus lesion after renal ultrasonography. Subsequent abdominal enhanced computed tomography (CT) and magnetic resonance imaging (MRI) of the kidneys showed DCS and a soft tissue mass with mild enhancement at the lower right renal sinus. The lesion was suspected to be a malignant renal pelvic carcinoma. Hence, the patient underwent a right radical nephrectomy. Histological examination revealed hyperplastic lymphoid follicles in the renal sinus. A detailed review of the patient's CT and MRI images and a literature review suggested that the lesion was hypointense on T2-weighted images and hyperintense on diffusion-weighted image manifestations, and showed mild enhancement, which distinguished the plasma cell type of CD from many other renal sinus lesions. Furthermore, peripelvic soft tissue masses with a smooth internal surface of the renal pelvis were on imaging findings, which suggests that the urinary tract epithelial system is invulnerable and can be used to differentiate the plasma cell type of CD from malignant lymphoma with a focally growth pattern to some extent.

Conclusion: Preoperative diagnosis is often difficult in such cases, as plasma cell type of CD involving only the right kidney is exceedingly rare. However, heightened awareness of this disease entity and its radiographic presentations may alert one to consider this diagnosis.