Bone metastasis of Wilms' tumor with monophasic epithelial histology in a young adult.

A unique case of Wilms' tumor with monophasic epithelial histology in the bone metastasis at initial presentation in an 18-year-old Taiwanese girl is presented. Histologically, a purely differentiated epithelial component in the L1-3 vertebrae was noted, which is consistent with the epithelial component in primary Wilms' tumor of the kidney by both microscopy and immunohistochemistry. Hence, Wilms' tumor should be included in the differential diagnosis of a metastatic lesion presenting a purely epithelial histology in a young adult or a child.