Tensin2 as a Novel Diagnostic Marker in Pediatric Gastric Gastrointestinal Tumors (GIST)

Background: Gastrointestinal stromal tumors (GIST) in pediatrics are unique and distinct from those in adults. Pediatric GISTs have rare clinical and pathological manifestations. Since the expression of the GIST immunohistochemistry markers is comparable in gastrointestinal sarcomatous tumors, novel IHC markers may be useful for some GIST diagnoses. Certain proteins, such as Tensin 2 “TNS2”, were found to be downregulated in most human cancers but overexpressed in GIST. Aim: This retrospective study aims to outline the pathological and clinical features of gastric GIST in this age group. So, we investigated the role of “TNS2” as a diagnostic immunohistochemical marker for pediatric GISTs. Materials and Methods: Forty patients with gastric GIST diagnosis confirmed by DOG 1 and C-KIT IHC; twenty-one with a spindle histology, 14 with epithelioid histology, and 5 of mixed type were enrolled and evaluated for “TNS2” expression. “TNS2” Protein expression was observed in both the cell membrane and cytoplasm. Cut-off points were assessed statistically. More than 10% of tumor cells had TNS2 protein, which was regarded as positive expression. Results: The highest “TNS2” expression is in spindle histology. More than half of the cases in the very low risk category strongly express “TNS2” in comparison with tumors in other risk categories. Results of “TNS2” were analyzed and expressed in terms of sensitivity and specificity, which showed high diagnostic accuracy for pediatric gastric GISTs. Regarding surgical parameters, Assessment of the surgical margin revealed that strong “TNS2” expression is associated with the presence of tumor infiltrates in >1 mm in the safety margin of the tumor. Conclusion: Our findings afford an idea regarding “TNS2's” efficacy as a sensitive and precise diagnostic immunohistochemical marker for pediatric stomach GIST.