Primary Iliocecal Gastrointestinal Stromal Tumor with Co-existent B/L Ovarian neoplasms: A Rare Case Report

Gastrointestinal stromal tumors(GISTs) are a heterogeneous group of tumors, previously thought to be tumors of smooth muscle differentiation, but now considered to arise from the interstitial cells of Cajal, that act as pace makers for peristalsis. Most frequent site is stomach (95%) followed by small intestine and less frequently involves esophagus, colon, rectum and rarely retro peritoneum respectively. GISTs are rare mesenchymal tumors, slightly more common in males; with peak age of 60 yrs. Majority of the GISTs have oncogenic mutations of the gene encoding tyrosine kinase c-KIT (CD 117). They are classified as tumors of low and high risk of malignancy depending on the size (> 5cms) and mitotic count (> 5/50 hpf) and associated features like tumor site and metastasis are also significant prognostic parameters. Other macroscopic alterations are tumor necrosis, mucosal ulceration, cystic degeneration, myxoid change and area of hemorrhage and calcification. Histologically, most GISTs are spindle cell tumors (67%) followed by other variants as epithelioid (13%), mixed and myxoid forms respectively and very rarely signet ring cell and extremely rare GANT variant. Other microscopic secondary alterations include cytonuclear pleomorphism, presence of multinucleated giant cells, inflammatory infiltrate and metastasis respectively. Criteria for assessment of degree of malignancy is number of mitoses per 50 hpf as major prognostic factor and tumor size in centimeters. They are further sub classified as tumors having very low degree of malignancy (9%), low degree (21%), intermediate degree and high degree as (47%). IHC study shows CD 117 positivity (97%), CD 34 positivity (63%) and high specificity for two types of antibodies namely SMA specific for smooth muscle tumors (24%) and S-100 for peripheral nerve sheath tumors (13%) respectively, because these tumors are often misdiagnosed as GISTs.