Wilms' tumour in Malaysian children: a histopathological study of cases encountered at the University Hospital, Kuala Lumpur over a 22-year period.

Formerly thought to have a constant incidence rate throughout the world, Wilms' tumour (nephroblastoma) has been shown to be less common among Asian children. A retrospective demographic and morphological study of Wilms' tumour histologically diagnosed over a 22-year period at the Department of Pathology, University Hospital, Kuala Lumpur was conducted to assess for inherent demographic and morphological differences between tumours in Malaysian children and those of Western populations. Thirty-seven cases of histologically proven Wilms' tumour qualified for inclusion in this study. 19 patients were Chinese, 13 Malay, 4 Indian and 1 Anglo-asian. 21 were male and 16 were female (M:F ratio = 1.3:1). Their ages ranged from 1 month to 4 years. 70.3% of the patients were below 2 years of age. 36 cases had unilateral and 1 bilateral tumours. Of unilateral tumours, 19 involved the left kidney and 17 the right. Histological assessment, based on criteria of the National Wilms' Tumor Study Group, revealed 20 (52.6%) tumours with a mixed pattern while 8 (21.1%) showed epithelial, 7 (18.4%) blastemal and 3 (7.8%) stromal-predominant patterns. Anaplasia was observed in only 2 tumours (5.3%). There was no obvious difference in age range and sex distribution, laterality of tumours and incidence of anaplasia between this and Western studies. No ethnic predilection was observed. A notably larger percentage of cases were below 2 years of age. Also, a larger proportion of epithelial-predominant and a lower proportion of blastemal-predominant tumours was observed compared with patterns reported from Western populations.