An in vivo staining test with 0.2 per cent methylene blue was applied to 129 patients with bladder tumor and 16 patients with chronic cystitis within a 6-year interval. Although normal mucosa did not pick up the stain nonpapillary in situ and microinvasive carcinomas did so frequently. Moderate dysplasia was stained in about half of the patients. The intensity of the stain in papillary tumors was correlated with the histologic anaplasia (grade). Grade 1 tumors were stained poorly or unstained in 86 per cent of the tests, whereas grades 2 and 3 tumors picked up the stain in 74 and 96 per cent of the tests, respectively. Even a tiny tumor, if poorly differentiated, was identified easily by the blue stain. The histologic anaplasia of tumors could be assessed roughly according to the intensity of the stain. However, chronic cystitis occasionally took up the stain, especially in cases of marked inflammatory infiltrate a deep stain was recognized. To differentiate nonpapillary early cancer from chronic cystitis the addition of a cytologic examination may be necessary.

A rare case of radiation-induced malignant mixed mesodermal tumor of the bladder is reported. A 78-year-old woman complained of hematuria, which originated from a polypoid tumor in the bladder 15 years after radiotherapy for squamous cell carcinoma of the uterine cervix. The bladder tumor recurred 9 months after resection and partial cystectomy then was performed. Histological findings revealed malignant mixed mesodermal tumor composed of carcinomatous and sarcomatous elements. The former element consisted mainly of transitional cell carcinoma with occasional foci of squamous metaplasia and glandular differentiation, while the latter consisted of spindle cell sarcoma showing partly cartilaginous and osseous differentiation. The histogenesis of malignant mixed mesodermal tumor of the bladder also is discussed.

Wereportthefirstcaseofchromophobecell renal carcinoma in chi1dhood.A 12-year-old boy presented gross hematuria following minor trauma. He was diagnosed as having a left renal tumor 45-mm in diameter. Radical nephrectomy was performed. One year later the boy was well.Int J Urol 1998;5:92-93

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