Delineation and documentation of anatomy in the presence of significant mass pathology presents a diagnostic challenge. This often necessitates the implementation of more than one imaging modality in order to perform an adequate assessment. We present a three-year old boy with extensive distortion of mediastinal anatomy secondary to pleural metastases from a Wilms tumour. This limited the ability to accurately assess mediastinal anatomy and cardiac function at baseline. Reassessment following initiation of chemotherapy showed a significant reduction in size of metastases with complete resolution of the mediastinal distortion.peer-reviewe