Nongestational choriocarcinoma can arise from germ cell or trophoblastic differentiation within endometrial carcinomas. Gestational choriocarcinomas are mostly seen in women of reproductive age, generally within 1 year after a molar or nonmolar pregnancy. The risk of developing choriocarcinoma is exceptional before 20 years of age but increases significantly from 40 years onward. Nearly 30% of patients with choriocarcinoma present with metastasis on diagnosis. The tumor has a tendency to disseminate hematogenously. Lung, vagina, and brain metastasis occurs in 50%, 30%, and 10% of cases, respectively; liver and kidney metastasis is less common [5
]. Urological involvement with gestational trophoblastic neoplasia is relatively rare, but renal involvement may cause massive retroperitoneal hemorrhage [4
]. Renal metastases can cause abdominal pain, hematuria, or oliguria but are more usually found as incidental mass lesions during radiological staging.
According to the International Society for the Study of Trophoblastic Disease, the incidence of renal metastases from choriocarcinoma is rare and can result in perinephric hemorrhage and lead to spontaneous rupture. Renal involvement can also present with hematuria [6
]. The case we reported here presented with gross hematuria originating from the right kidney that was confirmed by cystoscopic evaluation. Additionally, no evidence of other metastasis was determined except for the lesion in the lung, which could not be diagnosed by fine-needle biopsy. Wang et al reported that renal metastases were invariably preceded by lung metastasis (100%), indicating that renal metastasis is most likely the result of dissemination of tumor cells through the general circulation secondary to lung metastasis [7
]. However, this seems not to have been the case in our patient, in whom dissemination of lung metastases occurred after radical nephrectomy.
Choriocarcinoma is preceded by a hydatidiform mole 60% of cases, by previous miscarriages in 23%, by full-term pregnancy in 10%, and is primary in 5% of cases. Our case had a choriocarcinoma with a history of a hydatidiform mole 5 years previously.
The International Federation of Gynecology and Obstetrics (FIGO) staging for trophoblastic diseases that was devised in 1992 was improved in 2002 by combining the basic anatomic staging with the modified WHO risk factor scoring system [8
]. The diagnosis and treatment of choriocarcinoma is based on the biological behavior of the tumor rather than a histopathological diagnosis. The histological choriocarcinoma does not add to the risk score by the FIGO system. Use of the FIGO staging system is essential in determining initial therapy for patients with gestational trophoblastic neoplasia to ensure the best possible outcomes with the least morbidity. Our case was staged as IV: 20 according to the FIGO 2002 scoring system.
Patients with high-risk metastatic gestational trophoblastic neoplasia (FIGO stage IV and stages II-III score 7) should be treated initially with multiagent chemotherapy with or without adjuvant surgery or radiation therapy [9
]. Multiagent chemotherapy, a combination of etoposide, high-dose methotrexate with folinic acid, actinomycin D, cyclophosphamide, and vincristine (EMA-CO), results in improved remission and survival rates. Virtually 50% of high-risk patients require surgical treatment during the course of treatment [10
In conclusion, this case demonstrates that metastatic choriocarcinoma can present with flank pain, hematuria, and a renal mass imitating renal cell carcinoma. Also interesting in our case was the occurrence of bilateral renal masses followed by disseminated multi-organ metastases at 5 years after a hydatidiform mole treated with total abdominal hysterectomy and bilateral salpingo-oophorectomy. The patient was referred to medical oncology after the right radical nephrectomy and is still undergoing a chemotherapy protocol.