Complete Spontaneous Regression of a Primary Renal Cell Carcinoma. Report of a Pathological Proven Case and Review of the Literature

Regression of primary renal cell carcinoma (RCC) is a rare phenomenon and for several reasons many of the reported cases have been questioned. We present a case that can be considered a true spontaneous and complete regression of a primary RCC. A 79-year-old female underwent nephrectomy because a renal tumor. At the time of surgery image studies showed a small para-aortic lymph node. The tumor measured 3cm and was analyzed completely. Histology showed a fibro-inflammatory lesion with necrosis, foamy macrophages and inflammatory cells. No neoplastic cells were observed and the lesion was interpreted as a localized type of xanthogranulomatous pyelonephritis. One year later a CT control scan, showed that the para-aortic lymph node had increased in size to 4cm. Fine needle aspiration revealed features of clear RCC. Metastatic dissemination was limited so surgical removal of the para-aortic lymph node was performed and the cytologic diagnosis confirmed.