DOI: 10.36347/sjmcr.2015.v03i06.019

Pages: 512-514

Gastrointestinal stromal tumors (GISTs) neoplasms develop from pleuripotent stem cells that are programmed to differentiate into interstitial cells of Cajal and smooth muscle cells. A 47 year old male who was operated previously for malignant GIST of the small bowel presented with massive ascites. Cytologic examination of the ascitic fluid showed three-dimensional clusters of atypical spindle to epithelioid cells with indistinct cell borders, scant to moderate amount of cytoplasm and large oval to round hyperchromatic nuclei. Based on the cytologic morphology and clinicopathologic co-relation a diagnosis of malignant peritonitis due to metastasis from malignant GIST was made. The cytologic diagnosis is difficult as these lesions mimic other common tumors which include adenocarcinoma, smooth muscle tumours and schwannomas. Demonstration of CD117 or DOG1 antigen can clinch the diagnosis. The identification of GIST is essential for focused management, since GIST is the first model for targeted therapy in oncology.