Background. High-grade neuroepithelial tumor with areas resembling medulloepithelioma was diagnosed in an infant with coccygeal and inguinal masses. Hemihypertrophy is associated with Wilms tumor, hepatoblastoma and pancreatic tumors in children.

Case. The authors report on the first case of peripheral HNET associated with hemihypertrophy in an infant, with special discussion on histopathological differential diagnosis and management of this rare and highly malignant tumor.

Conclusions. HNET should be included into the list of hemihypertrophy associated tumors. Complete surgical excision with free margins is essential for the successful treatment of such cases and should be tried in suitable cases at the time of diagnosis. Continued treatment should be decided individually on a case to case basis.

Keywords: coccygeal, hemihypertrophy, high-grade neuroepithelial tumor, infant, inguinal, medulloepithelioma, tumor