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Primitive neuroectodermal tumour of the kidney with spontaneous regression of pulmonary metastases after nephrectomy

A 23-year-old women was admitted complaining of a 7-month history of general fatigue, slight fever, right flank pain and gross haematuria. CT showed a a 13 ¥ 10 cm right renal mass (Fig. la) and several nodules in both lungs, suggesting multiple pulmonary metastases. CT and cavography revealed a filling defect in the right renal vein and the inferior vena cava (IVC), suggesting a tumour thrombus in both (Fig. la). Aortography showed the mass to be hypervascular (Fig. lb). She underwent radical nephrectomy with cavotomy under a diagnosis of metastatic RCC with IVC tumour thrombus. The pulmonary metastatic lesions decreased in size and number 14 days after surgery (Fig. 1c) and subsequently increasingly regressed with time. At 2 months after surgery they had completely regressed (Fig. 1d) . Before surgery her urinary excretion of homovanillic acid (HVA) and vanillylmandelic acid (VMA) were 3.3 and 3.3 mg/day (within the normal ranges; HVA 1.5–6.6 mg/day; VMA 1.3–5.1 mg/day). The histological findings of the resected tumour showed the typical small round to ovoid tumour cells and several neuroblastic Homer Wright rosettes, suggesting the tumour to be a primitive neuroectodermal tumour (PNET) or neuroblastoma (Fig. 2a). Positive reactions were obtained with the antibodies against synaptophysin, neurone-specific enolase, S100 protein and CD99 (MIC2) [1] (Fig. 2b) but not to chromogranin and neurofilament. Taken together, the histological findings and laboratory results suggested a diagnosis of PNET of the kidney. The resection of the primary lesion was probably responsible for the complete regression of the pulmonary metastases. The patient remains well 1 year after surgery.