Rhabdoid tumour of the kidney: A clinicopathological study of 22 patients from the International Society of Paediatric 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 tumour (primitive neuroectodermal tumour). None of the children presented with stage I disease, five (23%) had stage II, ten (46%) stage III, and five (23%) stage IV disease. Two (9%) patients had bilateral tumours. Histologically, the vast majority (20/22) of the tumours exhibited a classical pattern but other histological patterns were also noted. Immunohistochemical studies performed in 12 cases showed vimentin positivity in all cases, CAM 5.2 in eight, epithelial membrane antigen in six, neuron specific enolase in four, S-100 protein in eight, and desmin in one case. In only 12 of the 22 tumours was there agreement between 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 another ten cases the initial diagnosis was changed by the panel to rhabdoid tumour. Metastases developed in 18 (82%) of the children-in eight they 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 children with adequate follow-up, only two (10.5%) with stage II disease are alive, while 17 (89.5%) died 2 weeks to 20 months after the diagnosis.