Primary renal synovial sarcoma: A case report

RATIONALE: Synovial sarcoma (SS) is a malignant neoplasm that arises from soft tissues proximal to the joints. It occurs primarily at the major joints of the extremities, but may also occur in the deep soft tissues around the joints. While primary renal synovial sarcoma (PRSS) is extremely rare, it is important to have a better understanding of their imaging and clinical features to establish an effective treatment plan. Correct identification of PRSS is also useful for treating renal neoplasms. PATIENT'S CONCERNS: A 56-year-old Chinese man was admitted to our hospital due to moderate, paroxysmal left-sided loin pain. DIAGNOSIS: Renal enhanced computed tomography (CT) scanning showed a relatively hypovascular lesion with calcification in the left kidney. A radical nephrectomy was performed in the left kidney. Postoperative pathology indicated SS with necrosis. The immunohistochemical findings were as follows: 34βE12 (Epithelium+), Bcl-2(+), CD99(+), CK-pan((Epithelium+), EMA(Epithelium+), Ki-67(+60%), and Vimentin(+), CD34(−). INTERVENTIONS: The patient underwent radical left nephrectomy with no complications. OUTCOMES: After discharge, a close review for 3 months showed no evidence of recurrence. LESSONS: PRSS should be considered for the differential diagnosis of renal hypovascular tumors. When problems arise in distinguishing renal hypovascular tumors, surgical pathology is helpful in the final diagnosis and further treatment of the disease.