Relapsed Wilms' Tumor Presenting as Metastasis to the Zygoma

Wilms' tumor accounts for the majority of renal tumors in children. Rarely, Wilms' tumor may metastasize to the bone. We present a case of a 15-month-old female who presented with severe abdominal distension and signs of cachexia. Abdominal ultrasonography and radiography of the abdomen both demonstrated a large abdominal mass. Follow-up computed tomography of the abdomen revealed a heterogeneous intra-abdominal mass arising from the left kidney which was surrounded by a thin rim of renal parenchyma. Biopsy of the mass revealed findings consistent with Wilms' tumor. The patient was 14 months status-post nephrectomy and chemoradiation but returned to the clinic with left facial swelling. Magnetic resonance imaging of the face demonstrated a multilobulated, heterogeneously enhancing solitary mass lesion in the left temple centered in the left zygoma with signs of bone breakdown. Despite its rarity, metastatic Wilms' tumor to bone should be considered in a child presenting with a new focal mass overlying bony-structures.