To collect and analyze clinical and pathological features of primitive neuroectodermal tumor (PNET)/Ewing sarcoma (EWS), a rare tumor occurring most commonly in bone and soft tissues of young people, which rarely occurs as a primary renal neoplasm and exhibits highly aggressive biological behavior.

All cases of PNET/EWS published from 1975 to February 2012 were collected. When available, clinical and pathological data were extracted for each case. Survivals were estimated with the Kaplan-Meier method and compared with the log-rank test with 95% confidence interval (CI).

A total of 116 cases were found. All patients had clinical symptoms as first presentation of disease such as pain (54%), hematuria (29%), and bulky renal mass (28%). Sixty-six percent of patients had stage IV disease at diagnosis. Median disease-free survival (DFS) was 5.0 months (95% CI 2.4-7.6). The probability to be alive at 18 months was 60% and 85% for patients with metastatic disease (M1) or not (M0) at diagnosis, respectively. Median overall survival (OS) was 24 months (95% CI 4.5-15.1) in patients with M1 disease, whereas it was not reached in patients with M0 disease (P <.001). In patients with M0 disease, 50% received neoadjuvant chemotherapy and the 12-month OS was 93% compared to 75% of untreated patients (P = .092). In patients with M1 disease who underwent treatment, the median progression-free survival (PFS) was 22.0 months (95% CI 17.9-26.1) with a clinical benefit in 74% of cases.

Our findings suggest that PNET/EWS is a rare aggressive tumor affecting principally young people, with a poor prognosis for patients with M1 disease; chemotherapy is an effective strategy in M1 disease and probably also in M0 disease.