Gastrointestinal stromal tumor penetrating into the small intestine in a patient with neurofibromatosis type 1

A 53-year-old woman with neurofibromatosis type 1 (NF-1) suddenly experienced left lower abdominal pain. Next day she was referred to our hospital for further examinations because her white blood cell count and C-reactive protein levels were elevated. Computed tomography revealed a >10 cm mass in the mid-abdomen. The mass contained air-fluid level material encapsulated by a thickened wall. Because gas was observed in the tumor, a fistula was suspected between the abscess in the mass and the small intestine. The association of the tumor and NF-1 indicated that the mass was a gastrointestinal stromal tumor arising from a part of the small intestine communicating with the gut, which resulted in abscess formation. An emergency operation was performed on the day of admission, and the tumor was removed by resecting the 2 intestinal loops by adhesiolysis. Few disseminated daughter nodules were also identified on the surface of the distant intestine. The patient was discharged from the hospital on the 10th postoperative day with no complications. Because of the remaining lesions, molecular targeted chemotherapy with 400 mg/day imatinib was initiated. There has been no sign of progression in past 18 months.