A 54-year-old man presented to a local hospital with right flank pain that was believed to be caused by cholecystitis. And abdominal ultrasound revealed a hypo-echoic area measuring 2.5cm × 2.3 cm in the right renal collecting system. The patient denied back pain, gross hematuria, urinary frequency, urinary urgency, and urodynia.
Computerized tomography (CT) scan and magnetic resonance imaging (MRI) revealed a mass in the right kidney with extension into the right renal vein and inferior vena cava, and further extension into the right atrium (Fig. A). Retrograde urography confirmed that the right renal pelvis was compressed and distorted, but was unobstructed. The right ureter also was unobstructed. Digital subtraction angiography revealed tumor thrombus in the inferior vena cava extending from the level of the right renal vein to the right atrium (Figs B). Laboratory investigations revealed no abnormalities. Renal function tests were normal. Urine analysis revealed no microscopic hematuria.
Figure 1 Multi-plana Reconstruction of CT scan before operation showing a mass in the right renal area and propagation through the inferior vena cava into the right atrium 1A (left). Digital subtraction angiography performed before surgery showing huge tumoral (more ...)
The patient was transferred to our hospital for further evaluation and treatment. Based on the clinical findings and investigations, a preliminary diagnosis of renal carcinoma of the right kidney was made. The patient underwent a right radical nephrectomy in a thoraco-abdominal procedure. At the same time, the tumor thrombus was removed from the inferior vena cava and the right atrium.
The resected right kidney measured 14cm×8cm×6 cm. Near the renal pelvis was a tumor measuring 7cm×5cm×4.5 cm with extension into the renal vein. On cut section, the mass had a solid and multicystic appearance with focal invasion of the renal parenchyma. The cysts measured from 0.5cm to 1.5 cm in diameter, and were filled with clear colorless fluid. The solid area was gray and uniform, without necrosis or hemorrhage. The tumor distorted but did not infiltrate into the renal pelvis. The paraortic lymph nodes and the right adrenal gland showed no evidence of tumor. Macroscopically, the tumor thrombus measured 25cm×1.5cm×1.5cm, and was gray with a myxoid cut surface.
Histologically, the tumor exhibited a triphasic pattern of blastema, epithelium, and stroma with myxoid background in the solid area and in the septa of the cystic area (Figs ). The lining cells of the cysts ranged from flattened to columnar, occasionally of “hobnail” type, and showed positive staining for cytokeratin (Fig A) and EMA. Interestingly, the majority of the cysts had distinct walls composed of spindle or oval cells that expressed muscle-derived markers, such as smooth muscle actin (1A4) and muscle actin (HHF35) (Fig B). There were no anaplastic components. Focal renal parenchymal invasion could be seen. The histologic features of the thrombus were similar to those of the renal tumor. Thus, the final diagnosis was favorable histology WT (partially differentiated type), with renal vein invasion and extension to the inferior vena cava and right atrium.
Figure 2 Histological examination of the adult WT. 2A (left) representative of the cystic area. The lining cells of the cysts, ranged from flattened to columnar, were occasionally of “hobnail” type, and the cysts had distinct walls composed of (more ...)
immunohistochemistry staining of the adult WT. 3A (left) The lining cells of the cysts showed positive staining for cytokeratin and 3B (right) the spindle or oval cells of the cysts walls expressed muscle actin [×200] .
The patient received nine courses of adjuvant chemotherapy postoperatively, including two courses with Dactinomycin, Adriamycin, and Vincristine, two courses with Paclitaxel and Carboplatin, four courses with Paclitaxel, Ifosfamide, and Mesna, and one course with Vinorelbine and Dactinomycin. Multiple metastases to the liver, lung, and chest wall were occurred within 12 months after surgery, and the patient was dead from the disease 14 months later.