A primitive neuroectodermal tumor (PNET) is a small round cell tumor that arises from the nerve crest. This tumor usually occurs in the central nervous system or soft tissue, but it can occur in the kidney in rare cases. Herein we report a case with severe multiple liver metastases after surgery for right renal PNET. The patient was a 21-year-old man with a chief complaint of right abdominal pain. Hemorrhage in a right renal malignant tumor was diagnosed, and radical nephrectomy was performed. Histopathology showed bare nuclear round atypical cells with a scarce cytoplasm proliferating like a seat and nest. Some of the cells formed a rosette structure and the tumor cells were positive for CD99, leading to diagnosis of PNET. Severe multiple liver metastases occurred 6 months after surgery, and six courses of chemotherapy with ifosfamide, etoposide and doxorubicin were performed. After this treatment, residual tumor was removed, but the tumor cells were absent histologically.
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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