Endodermal sinus tumour of the omentum in a child.

Endodermal sinus tumour usually arises in a gonad; extragonadal endodermal sinus tumours are rare. We report a 3-year-old boy with an endodermal sinus tumour arising in the greater omentum, which may be the second reported case in the English literature. He presented with a solid mass in the upper abdomen and a markedly raised serum alpha-fetoprotein (AFP) level. Following percutaneous needle biopsy and omentectomy, histological examination revealed classic morphological features of an endodermal sinus tumour. This rare diagnosis is possible from the imaging features in association with a raised serum level of AFP.