Neurofibromatosis type 1 associated multiple and cystic gastrointestinal tumors: 02 case reports.

Introduction: GIST's are the most common mesenchymal tumor of the gastrointestinal tract, clinically and radiologically heterogeneous, only a histological study can confirm the diagnosis. The link between NF1 and GISTs have been established but not fully elucidated.

Case Presentation: we report 02 cases of NF1 associated GIST, a 60 years old woman with multiples GISTs in the duodenum, proximal jejunum and in the colon presenting an iron deficiency anemia due to chronic bleeding, operated with R0 resection and a low risk of recurrences and a 41 year old male patient with acute abdominal pain with a giant abdominal mass mimicking a hydatid cyst with no relevant medical history, diagnosed at the same time for typical clinical NF1, CT scan showed the cystic mass but did not confirmed its origin, a complete resection of the mass with no capsule fraction was tricky but successful and the histopathology found a high risk of recurrences. The 2 patients received adjuvant imatinib therapy with recurrence free survival at 12 months follow up. Our cases represents a rare entity (multiples GISTs and cystic GIST) within a rarest population (NF1 associated GIST).

Discussion: the diagnosis of NF1 is based on typical clinical criterias but the GISTs are known to be the variable, symptomatic or silent, small size or giant. Imaging is based on CT scan with intravenous contrast studying the vascular pattern, the extra intestinal and metastasis localizations. MRI is no superior, but useful in the study of pelvic GISTs and liver metastasis. Histopathology is the only way to confirm the diagnosis with marker staining with CD117 and DOG-1. The emerging imatinib, sunitinib and regorafinib are used as neoadjuvant or adjuvant therapies in GISTs with high or moderate risk of recurrences. No consensual guidelines are yet established for the follow up as the recurrences are more frequent.

Conclusion: GIST's association to NF1 is established, but the different aspects of the physiopathological, clinical and the treatment haven't been established yet with no larger population to study. We believe that the understanding of the development of this type of tumors within the NF type 1 group would allow a better treatment and follow up and may be can lead to screening.