Gastrointestinal Stromal Tumor - A Rare Case Report

Gastrointestinal stromal tumors (GISTs) are among the rare tumors of gastrointestinal tract with incidence of < 5%. GISTs arise from precursor cells of Interstitial cells of cajal (ICC). Tumors most frequently arises from stomach (60%), jejunum and ileum (30%) and < 5% of tumors of extra intestinal in origin. Mutation of c-KIT tyrosine kinase receptors form the basis of uncontrolled proliferation of cells leading to tumor formation. 89 year old female presented to Department of Surgery, ESIC - MC & PGIMSR, Rajajinagar, Bangalore- 560010, with history of pain abdomen for duration of 3 months. Patient had an epigastric intra-abdominal lump measuring around 15 x 20 cms. CT scan revealed intra peritoneal heterogenic mass arising from stomach. OGD was normal. Intra-operatively it was found out that the tumor was arising in greater omentum weighing 2.5 kgs and had no communication with stomach or transverse colon. Histopathology of the specimen confirmed the diagnosis of primary Omental GIST. Post-operative follow-up was uneventful. CD 117(c-KIT) is used as a biomarker for identification of GISTs in tumor tissue. GIST occurs in patients older than 50 yrs. of age and symptom depends on mass effect. Diagnosis needs high degree of suspicion and confirmed by radiology and histology. Immunohistochemistry is used in estimation of level of positivity for CD 117. Surgery is the primary modality of treatment in operable cases. Advanced GISTs and large tumors are treated with targeted chemotherapy by Imatinib Mesylate (anti tyrosine kinase receptor). Primary omental GIST occurs in <1% of patient and treatment is essentially in line of GISTs elsewhere. GIST as it is a rare tumor, there is paucity of data on proper management of the tumor and there is need for multispecialty approach for treatment of the disease.