Divergent gastrointestinal stromal tumors in syndromic settings

The vast majority of gastrointestinal stromal tumors (GISTs) occur as sporadic tumors. Rarely, however, these neoplasms can arise in syndromic contexts. Under these circumstances, GISTs are often multiple and associated with accompanying signs peculiar of the hosting syndrome. Moreover, syndromic GISTs themselves tend to show heterogeneous features depending on the underlying condition. Multiple inflammatory fibroid polyps (IFPs) and a jejunal spindle-cell GIST were resected in a germline PDGFRA-mutant individual. Although the association of IFP and GIST is typical of this genetic setting (PDGFRA mutations can in fact trigger both these tumor types), PDGFRA-mutant GISTs are usually epithelioid and gastric. This discrepancy was settled evidencing a somatic KIT mutation in the GIST. The awareness of possible somatic mutations can be critical in the management of high-risk/malignant GISTs arising in syndromic settings. GIST features unusual for a given GIST-predisposing syndrome are a valuable tool in the hands of physicians for suspecting these "extra" triggers, which could not be sought for once a diagnosis of GIST-prone syndrome is well established, in a bona fide cost/benefit perspective.