[Explosive metastasis of a cancer of the kidney pelvis in analgesic kidney].

A 48-year-old male experienced sudden pain in the right flank and macrohematuria with subsequent repeated episodes of painless macrohematuria. In the radiological work-up, CT was interpreted as inflammatory enlargement of the right kidney and MRI diagnosed renal vein thrombosis. There was some suspicion that there might be a malignancy. Five months later the patient had to be admitted to the hospital, because of increasing flank pain, desiccation and general signs of inflammatory disease. Radiological changes compatible with pulmonary metastases were found. Biopsy of enlarged mediastinal lymph nodes revealed undifferentiated carcinoma. Because of the expression of Cytokeratin primary urothelial carcinoma was suspected. The patient then deteriorated rapidly. No further specific therapy could be carried out. Death was chiefly caused by respiratory insufficiency 5 months after the first episode of pain and 1 month after admission. Autopsy revealed a poorly differentiated urothelial carcinoma of the right renal pelvis, with extensive carcinomatous angiomatosis and metastases to the left kidney, lungs, and regional and mediastinal lymph nodes. Independently of the carcinoma, both kidneys also showed interstitial nephritis, papillary necrosis and capillarosclerosis, compatible with analgesic-user kidney ("phenacetin kidney") in the absence of a corresponding history.