Gastrointestinal Stromal Tumor Diagnosis

The clinical presentation that is typically observed with gastrointestinal stromal tumors (GISTs) is somewhat nonspecific, states Anthony P. Conley, MD. Patients may report symptoms related to anemia, such as fatigue and changes in skin color, usually in the chronic setting. GISTs can be detected through upper endoscopy or colonoscopy, notes Conley, but may escape detection because they tend to arise in the muscular layer rather than the epithelial portion of the gastrointestinal tract. Once GIST is suspected, it is important to conduct a biopsy to rule out other diseases, such as leiomyomas and leiomyosarcomas, comments Conley.

The majority of patients with GIST are asymptomatic, says Robert H. I. Andtbacka, MD, although they may present with abdominal discomfort and gastrointestinal bleeding. A GIST diagnosis is often discovered with CT scan of the abdomen, pelvis, and small bowel, explains Andtbacka. Colonoscopies also help confirm that the malignancy is not adenocarcinoma, which is more common in these locations than GIST, says Andtbacka.

Obtaining a core biopsy also allows for immunohistochemical staining for mast/stem cell growth factor receptor, also known as c-KIT (CD117), platelet derived growth factor receptor, and other receptors. Staining positive for these markers can also indicate a GIST diagnosis, as approximately 95% of GIST tumors express c-KIT.