Primary renal synovial sarcoma in a 13-year-old boy.

Primary renal synovial sarcoma is a rare entity with fewer than 40 cases reported in the literature. Its clinical presentation and radiographic features, namely, its often complex cystic appearance, make it difficult to differentiate from other benign or malignant renal lesions. Although there are certain consistent morphological and immunohistochemical features, diagnosis ultimately depends on molecular studies. Prognosis is poor, and there currently exists no defined treatment protocol. Herein, we describe the youngest reported case of primary renal synovial sarcoma in the literature.