C-kit negative extra intestinal gastrointestinal stromal tumor with no detectable mutations: A rare case

Abstract

Epithelial tumors are quite common in the gastrointestinal tract, but in addition there is a heterogenous group of mesenchymal tumors which are referred to as Gastro-intestinal stromal tumors (GIST). These may have different morphology like epithelioid or spindle cell but have a common immunohistochemical profile. Majority of them are positive for CD117(Less than 5% negative) those which are negative are almost always positive for DOG 1 antbody. These tumors are associated with the Gastro intestinal tract but a small percentage maybe extra-intestinal (less than 5%) This small subgroup is referred to as EGIST (extra intestinal GIST). We present a rare case which was negative for CD 117, but positive for DOG1 (demonstrated on GIST). The case was tested for mutations and was also negative which makes it a further rarity.