Inverted papilloma of the ureter is a rare tumor generally considered to be a benign lesion. We present a case of ureteral inverted papilloma with malignant transformation and review the literature. Ten cases of ureteral inverted papillary tumors in Japan and 13 cases of inverted papillary tumors associated with malignancy in the urinary tract in the world literature have been analyzed to define their features. Inverted papillary tumors of the ureter have distinct clinicopathological features, but most are discovered retrospectively after nephroureterectomy. From the standpoint of clinicopathological features, inverted papillary tumor of the ureter should be distinguished from its exophytic counterpart with respect to the treatment. If the tumor can be diagnosed macro- and microscopically during surgery as inverted papilloma or malignant inverted papillary tumor without invasion, partial ureterectomy including the lesion may be recommended. Furthermore, we propose the hypothesis that inverted papillary tumor could be a neoplasm of basal cell origin in the transitional epithelium, termed ‘basal cell urothelioma’.
Background: A total of 60 604 persons underwent a general health checkup at Toma Hospital, Saitama, Japan, between January 1993 and June 1997, and transabdominal ultrasonography (US) was performed on all persons. We investigated the usefulness of transabdominal US in detecting renal tumors during general health checkups. Methods: A definite diagnosis was made in cases where the re-examination by US revealed calculus with acoustic shadow or a simple cyst. Computed tomography (CT) was conducted in patients suspected of having a renal tumor, and a diagnosis of renal angiomyolipoma (AML) was made if plain CT gave evidence of a fatty component. Patients diagnosed as having a renal cell carcinoma (RCC) with non-uniform enhancement underwent nephrectomy. If a definite diagnosis could not be made even by contrast CT, the monitoring by US and contrast CT once a year was continued.Results: Of 97 (0.16%) patients whose transabdominal US findings indicated a diagnosis of suspected renal tumor, 58 underwent the re-examination by US; of these, CT was conducted in 47. Detailed US revealed a hyperechoic pattern in 44 patients, a mixed pattern in nine and an isohypoechoic pattern with internal echo in five. By plain CT, 24 patients were diagnosed as having AML, and two as having renal calcification. Contrast CT enabled a diagnosis of renal cyst to be made in two patients and renal tumor in 14. All 14 patients with RCC except one underwent nephrectomy, which provided pathologic evidence supporting the diagnosis. Five patients had a tumor unidentifiable by CT, with continuing periodic follow-up by US and CT. Eleven patients underwent no CT.
Conclusion:Of the 60 604 persons who underwent a general health checkup, we found 14 cases of RCC and 24 cases of AML. As a small RCC has a favorable prognosis, patients greatly benefit from early detection; therefore, we should recognize the importance of identifying renal masses by US screening during general health checkups.
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