Malignant gastrointestinal stromal tumor in a patient with neurofibromatosis type 1.

Neurofibromatosis type 1 (von Recklinghausen's disease, NF-1) is an autosomal-dominant neurocutaneous disorder characterized by abnormal skin pigmentation (café au lait spots and axillary freckling), cutaneous and plexiform neurofibromas, skeletal dysplasias, and Lisch nodules (pigmented iris hamartomas). Gastrointestinal stromal tumors (GISTs) are the most common tumors of mesenchymal origin in the gastrointestinal tract, mesentery, omentum, and retroperitoneum. Here, we report a case of GIST in the ileum of a 76-year-old woman previously diagnosed as NF-1. She was admitted due to sudden onset of abdominal pain. Contrast enhanced CT scan revealed a moderately defined, peripherally enhanced soft tissue mass of about 8.8 x 7.3cm, originating from the small bowel in the left of the abdomen. Surgical excision was performed and the tumor was found to be composed of tumor cells that were positive for c-kit protein. The patient started imatinib treatment a month later, but stopped medication due to dyspepsia after a few months and eventually progressed after 18 months.