A unilateral teratoid Wilms' tumor with raised serum alpha-fetoprotein level.

Teratoid Wilms' tumor with raised serum alpha-fetoprotein level is an unusual type of tumor. We, here, describe a twelve month old boy presenting with lumbar mass. Clinical features, radiological findings, gross examination, and histomorphological features are studied, and various differential diagnoses like Wilms' tumor with heterologous elements, intrarenal teratoma and metastatic germ cell tumor are taken into consideration.