Renal and extrarenal rhabdoid tumors in children: a clinicopathologic study of 14 patients.

The clinical and pathologic features of 14 children with rhabdoid tumors are presented. Eight patients had primary renal neoplasms and six had extrarenal tumors. The eight renal rhabdoid tumors were identified among 514 primary renal neoplasms collected at four pediatric institutions. Six patients were under 1 year of age; five children died of tumor-related causes, four of them within 4 months of diagnosis and one 17 months postnephrectomy. Another patient died of sepsis 12 days postnephrectomy. One is alive 13 months postnephrectomy, and one was lost to follow-up evaluation. The most common sites of metastasis were the lymph nodes (seven children) and the lungs (three patients). Three infants with renal rhabdoid tumors had, in addition, intracranial masses, two of which manifested clinically before the detection of the renal tumors, in one confirmed to be a primitive neuroectodermal tumor. Five of the 6 extrarenal tumors were identified among 155,926 surgical pathology specimens examined in the same children's hospitals over the same period of time; the remaining extrarenal rhabdoid tumor was received in consultation from a community hospital. The extrarenal rhabdoid tumors occurred in the dorsum of the right foot, liver, soft tissue of the right chest wall, left temporal lobe, left leg, and left thoracic paraspinal region. The ages ranged from 6 weeks to 15 years and two months. Three patients died of tumor-related causes within 4 months of diagnosis; one was a term stillborn. Two are alive, 1 month and 70 months postdiagnosis. Common sites for metastases included the lungs (three patients), and liver and lymph nodes (two children each). Patients with renal and extrarenal rhabdoid tumors are of similar age, have a similar clinical course, with early metastases and poor response to therapy. Primitive neuroectodermal intracranial tumors have been identified in several reported patients with renal rhabdoid tumors; similar brain tumors have not been documented in patients with extrarenal rhabdoid tumors. The histogenesis of this tumor remains unknown.