We report a six-year-old Malay girl who presented with a right retroperitoneal tumour that measured 7.5 cm in diameter. A wide excision of the lesion was performed. The tumour was separated from a normal-appearing right kidney by a capsule. Microscopically, this well-encapsulated tumour was composed of classical triphasic components: epithelial, mesenchymal and blastemal areas. The immunohistochemical study showed WT1 expression in the blastemal area. Thus, a diagnosis of Wilms' tumour with favourable histology was made. The patient was well for 12 months. Extrarenal Wilms' tumour is uncommon, with the majority of cases occurring in the retroperitoneal and inguinal areas. Wilms' tumour that is not arising from the intrarenal area but shares a common capsule with the ipsilateral kidney, is even rarer. Indeed, our case would be more appropriately classified as juxtarenal/pararenal Wilms' tumour. Despite its rarity, an extrarenal or even juxtarenal/pararenal Wilms' tumour should be included in the differential diagnosis of retroperitoneal tumour.
We report the clinical features and in vitro chemosensitivity assay findings of a 13-year-old girl who developed secondary B-cell acute lymphoblastic leukemia (ALL) 7 years after a diagnosis of Wilms' tumor. The patient was treated using the Berlin - Frankfurt - Muenster (BFM) ALL chemotherapy protocol with poor response to initial therapy before succumbing to sepsis. An in vitro chemosensitivity assay on her peripheral blood lymphoblasts was performed while she was undergoing induction therapy and showed a high level of resistance to drugs commonly used for ALL therapy, e.g. steroids, anthracyclines, vincristine and L-asparaginase. The mechanism of chemoresistance was not elicited, but was probably not related to P-glycoprotein (P-gp) over-expression. We believe that the in vitro chemosensitivity assay is a good indicator of cellular response to chemotherapy and may provide reliable information for the basis of the selection of drugs to be used for the treatment of similarly rare patients rather than relying on "standard" protocols.