Gastrointestinal stromal tumors (GISTs) are mesenchymal tumors of the alimentary 
tract rarely observed in children. The treatment of choice for GIST is surgical 
resection. Although the prognosis of GISTs with low malignant potential is 
excellent, high-malignant-potential GISTs have a high rate of recurrence. 
Prognostic factors such as tumor size, mitotic rate and presence of metastases 
may provide an indication for adjuvant imatinib mesylate (IM) treatment. Here we 
present a young patient with a large GIST with high-risk features who is in 
complete remission after surgical excision and adjuvant IM treatment. This 
patient is the only colon-located CD117-positive case where IM was administered. 
The exact indications as well as the optimal dose and duration of IM need to be 
clarified with the contribution of new cases and the growing experience of this 
rare disease.