Multiple sporadic gastrointestinal stromal tumors concomitant with ampullary adenocarcinoma: a case report with KIT and PDGFRA mutational analysis and miR-221/222 expression profile.

GISTs originating multifocally at different GI sites, in patients lacking familial syndromes, could be interpreted as recurrent/metastatic disease. MiR-221/222 have recently been identified as regulators of KIT expression in GISTs. We report the first case of synchronous GISTs in the stomach and duodenum concomitant with an ampullary adenocarcinoma. Different CD117 expression patterns could be related to different KIT mutational status in the two lesions: gastric GIST showed a dot-like pattern and lacked KIT mutations; duodenal GIST had a strong membranous expression pattern, likely due to KIT exon 9 duplication, which is associated with lower response to imatinib. MiR-221/222 were downregulated in GISTs as compared with normal tissue (p<0.05) and expressed increased levels in the gastric GIST as compared with duodenal one (p<0.05). Our data support an independent origin of the two GISTs. Determining whether these tumors are multiple primaries or recurrencies is helpful to predict their malignancy and to select proper treatment.