Undifferentiated mesenchymal neoplasm of the esophagus in a child: case report and comparison with gastrointestinal stromal tumor.

Mesenchymal neoplasms of the esophagus are relatively uncommon in adults and exceedingly rare in children. Childhood tumors consist almost exclusively of smooth muscle tumors (leiomyomas). We report a case of an undifferentiated mesenchymal neoplasm occurring in the distal esophagus of a 15-year-old boy which is not a gastrointestinal stromal tumor. To our knowledge, this is the first reported case of such a neoplasm occurring in the esophagus of either an adult or child.