Fine-needle aspiration cytopathology in the diagnosis of Wilms tumor

BACKGROUND/PURPOSE The International Society of Paediatric Oncology (SIOP) protocol for Wilms tumor (WT) includes preoperative chemotherapy as the initial approach. However, an inadequate treatment may be performed in case of histological misdiagnosis. We evaluated the impact of fine-needle aspiration cytopathology (FNAC) in the diagnosis of unilateral WT in our group of patients. MATERIALS AND METHODS A retrospective descriptive study of patients with diagnosis of unilateral WT who underwent FNAC prior to neoadjuvant chemotherapy between 1993 and 2009 was performed. We reviewed the cytological diagnosis obtained by ultrasound-guided FNAC and the histological correlation with the resected specimens. RESULTS FNAC was performed in 66 patients with unilateral WT. In 57 of the 58 patients with positive FNAC for WT, the final diagnosis was correct (PPV: 98.2%). In 8 cases with negative FNAC for WT, the final diagnosis was positive for WT in 3 patients (NPV: 62.5%). Sensitivity was 95% and specificity was 83.3%. No complications were found associated with the procedure, except for an episode of haematuria, which resolved spontaneously. CONCLUSIONS FNAC is a useful and feasible technique in children that may confirm the suspected diagnosis of unilateral WT, avoiding inadequate preoperative chemotherapy in case of a non-Wilms renal tumor.