Multifocal gastric gastrointestinal stromal tumors (GISTs) with lymph node metastases in children and young adults: a comparative clinical and histomorphological study of three cases including a new case of Carney triad.

backgroundGastrointestinal stromal tumors (GISTs) are the most frequent mesenchymal tumors of the gastrointestinal tract usually occurring in the 6th to 7th decade of life, while their occurrence in children is rare (1-2%). Carney triad (CT), a non-hereditary association of gastric GIST with pulmonary chondroma and/or extraadrenal paraganglioma, is an even much rarer disease (to date ~120 cases reported worldwide) usually affecting young adult females. Pediatric GISTs differ from CT-associated GISTs solely by the absence of other components of the triad and are completely different from sporadic GISTs of the adult. Both, pediatric and CT-GISTs, metastasize frequently to regional lymph nodes (29%) and are usually wild type (WT) for common KIT-/PDGFRA mutations. CASE PRESENTATION AND

resultsWe compare one new CT GIST with two pediatric/young adult multifocal gastric GISTs presenting with lymph node metastases. We put special focus on histomorphological growth pattern in the primary tumors and in the metastases. The two cases of pediatric/young adult GIST without the other components of CT showed all the features of the triad: female gender, young age, multifocal antral-based gastric GIST with biphasic histological growth pattern, lymph node metastases, hypercellularity and WT status for common KIT-, PDGFRA- and B-RAF mutations. DISCUSSION AND

conclusionPediatric/CT-associated GISTs and sporadic GISTs of the adults differ significantly from each other with regard to patients' age, gender, tumor localisation, histomorphological growth pattern, mutational status and risk for metastasis. Our cases of pediatric/young adult GISTs show all characteristics of CT except for the absence of other components of the triad. Therefore these GISTs are probably not sporadic, but may represent either early manifestation or forme fruste of the CT. Thus, these patients need to be regularly examined for the development of extraadrenal paraganglioma or pulmonary chondroma.