We recently encountered an extremely rare case of spontaneous perirenal hemorrhage in a 34-year-old man. He initially had undergone radical nephrectomy owing to suspicion of renal cell carcinoma. The final diagnosis was extraskeletal Ewing sarcoma.
IntroductionEwing sarcoma (ES) is a poorly differentiated, aggressive malignancy that most frequently develops in bone, soft tissues, and the chest wall. Although the kidney has been increasingly recognized as an unexpected site for extraskeletal ES, 1 primary renal ES is still uncommon, furthermore, spontaneous rupture of primary renal ES is rarely reported. We present an extremely rare case of spontaneous perirenal hemorrhage because of renal ES.
Case reportA 34-year-old man presented to the emergency department with left flank pain for 1 day. He had no history of specific disease or trauma. Physical examination indicated moderate tenderness across the whole abdomen, which was more severe on the left side. No rebound tenderness was noted in the abdomen. However, severe costovertebral angle tenderness was present on the left side.He had a blood pressure of 140/90 mmHg, pulse rate of 95 beats/min, respiratory rate of 20 breaths/min, and body temperature of 37.7°C. A complete blood count was performed, the results of which revealed a hemoglobin of 14.3 g/ dL, a platelet count of 176 000/µL, a blood urea nitrogen level of 18.5 mg/dL, and a creatinine level of 0.92 mg/dL.An urgent contrast-enhanced computed tomography (CT) scan was performed (Fig. 1). We visualized a suspicious 6.8-cm mass originating from the upper pole of the left kidney, with internal necrosis and hemorrhage in the left perirenal space. The first impression of the radiologist was spontaneous rupture of renal cell carcinoma (RCC), and the second was fat depletion angiomyolipoma. On the third day of hospitalization, we performed a radical nephrectomy due to potential of malignancy.Macroscopic examination revealed a ruptured tumour mass with circumjacent hemorrhage, and the ruptured surface showed hemorrhagic and adipose tissue. Microscopically, the tumours were in the renal pelvis and ureter, infiltrating to the renal parenchyma (Fig. 2a). They consisted of uniform, small round cells with round nuclei containing fine chromatin, scanty clear, or eosinophilic cytoplasm, and indistinct cytoplasmic membranes (Fig. 2b). In the immunohistochemical analysis, the cells exhibited diffuse membranous positive staining with CD99 and vimentin, while cytokeratin was negative (Fig. 2c). The EWS-FLI1 fusion gene consistent with t(11;22) demonstrated by fluorescence in situ hybridization study (Fig. 2d). The pathologic diagnosis was high-grade extraskeletal ES.In addition, we performed a chest CT scan, whole body positron emission tomography (PET)-CT scan, and whole body bone scan that revealed no other pathologic site (primary origin). The final diagnosis was spontaneous perirenal hemorrhage of primary renal ES. He was discharged 10 days after nephrectomy, and received adjuvant chemotherapy (3 cycles of vincris...