Case presentation
A 4-year-old male was referred to the pediatric oncology unit after abdominal computed tomography (CT) performed for his swollen abdomen demonstrated a 15.7 cm heterogeneous mass on the upper pole of his right kidney. Furthermore, chest CT showed a right pleural effusion. On physical examination, there was a palpable, hard, nontender mass occupying the right hypochondrium and flank, extending down to the right iliac fossa and crossing the midline. As far as symptoms are concerned, the patient had unintentionally lost eight kilograms in one month and experienced intense sudoresis and enuresis.
Complete blood count and renal and hepatic function tests were within normal limits, while serum AFP was elevated, at 159.87 ng/mL (reference value <10 ng/mL). To evaluate his pleural effusion, the patient underwent ultrasound (US) examination of the thorax, which found evidence of chest cavity invasion by an abdominal mass measuring 14.9 x 12.2 x 9.9 cm (935.8 cm3). Due to the highly elevated tumor dimensions, it was not possible to determine its origin, whether renal or hepatic, requiring a biopsy for accurate identification of the primary tumor site. Anatomopathological analysis of the biopsied mass revealed a morphological picture that could correspond to a mixed HB or a triphasic WT — the former being composed of both an epithelial (fetal and embryonal) and a mesenchymal component and the latter of blastema, stroma and epithelial cells — so that an immunohistochemical analysis was strictly necessary for accurate diagnostic definition [13, 14]. Immunohistochemical analysis of the tru-cut biopsied mass was negative for hepatic markers, but expressed specific markers (cytokeratin AE1/AE3, CD57, integrase interactor 1 and Wilms tumor 1) compatible with triphasic nephroblastoma. The patient was thus diagnosed with stage IV WT.