A 28-year-old woman reported epigastralgia and constitutional syndrome of one month's duration. CT scan showed a 15 x 13 x 7 cm mass dependent on the ascending colon with bilobar liver metastases; a right hemicolectomy with liver biopsy was performed. Pathology showed a tumour consisting of spindle cells with high mitotic activity which, after ultrastructural examination and IHC, was diagnosed as GANT. Adjuvant treatment with imatinib 400 mg daily orally was performed. Follow-up CT scan at six months showed a partial reduction of liver metastases, complete remission at one year and after three years there was no evidence of local or distant recurrence.