RHABDOID TUMOR OF THE KIDNEY - A CLINICOPATHOLOGICAL STUDY OF 22 PATIENTS FROM THE INTERNATIONAL-SOCIETY-OF-PEDIATRIC-ONCOLOGY (SIOP) NEPHROBLASTOMA FILE

We present 22 (0.9%) cases of rhabdoid tumour of the kidney diagnosed amongst 2392 renal tumours in children. The patients ages ranged from 3 weeks to 94 months (median 7 months) and the female:male ratio was 1 .2 : 1. Clinically, they presented with an abdominal mass but four (18 %) children also had hypercalcaemia and one (4.5%) developed a brain t umour (primitive neuroectodermal tumour). None of the children present ed with stage I disease, five (23%) had stage II, ten (46%) stage III, and five (23%) stage IV disease. Two (9%) patients had bilateral tumo urs. Histologically, the vast majority (20/22) of the tumours exhibite d a classical pattern but other histological patterns were also noted. Immunohistochemical studies performed in 12 cases showed vimentin pos itivity in all cases, CAM 5.2 in eight, epithelial membrane antigen in six, neuron specific enolase in four, S-100 protein in eight, and des min in one case. In only 12 of the 22 tumours was there agreement betw een the reporting pathologist and the panel on a diagnosis of rhabdoid tumour of the kidney. Eight tumours originally diagnosed as rhabdoid tumour of the kidney were found to be other renal tumours and in anoth er ten cases the initial diagnosis was changed by the panel to rhabdoi d tumour. Metastases developed in 18 (82%) of the children-in eight th ey were present at the time of diagnosis and in 10 they developed from 2 weeks to 9 months after initial diagnosis. Metastases were found in the lung, abdomen, lymph nodes, liver, bone and brain. Of the 19 chil dren with adequate follow-up, only two (10.5%) with stage II disease a re alive, while 17 (89.5%) died 2 weeks to 20 months after the diagnos is.