Gastrointestinal stromal tumor (GIST) - Management approach and Surgery - Dr. Gunjan Desai - Part 2
Gastrointestinal stromal tumors (GISTs) can present with a variety of clinical symptoms and may be found incidentally during medical evaluations for other conditions. The clinical presentation of GISTs can vary depending on the size, location, and aggressiveness of the tumor. Here are some common clinical presentations and diagnostic modalities for GISTs:
Clinical Presentation:
Abdominal Pain: Many patients with GISTs experience abdominal pain or discomfort, which is often the most common symptom. The pain may be localized to the area of the tumor.
Gastrointestinal Bleeding: GISTs in the stomach or small intestine can cause bleeding, leading to symptoms such as hematemesis (vomiting blood) or melena (black, tarry stools).
Gastrointestinal Obstruction: Large GISTs can obstruct the gastrointestinal tract, causing symptoms like nausea, vomiting, and abdominal distension.
Palpable Mass: In some cases, a palpable mass or lump may be felt in the abdomen upon physical examination.
Fatigue: Anemia due to chronic gastrointestinal bleeding can lead to fatigue and weakness.
Weight Loss: Unintentional weight loss is a common symptom, often associated with more advanced or aggressive GISTs.
Asymptomatic: Some GISTs may be asymptomatic and discovered incidentally during imaging studies or surgeries for unrelated conditions.
Diagnostic Modalities:
Imaging Studies:
CT Scan: Computed tomography (CT) scans of the abdomen and pelvis are often used to visualize and locate GISTs. They can provide information about the tumor size, location, and any metastasis.
MRI: Magnetic resonance imaging (MRI) may be used to obtain detailed images of GISTs, particularly in cases where CT scans do not provide clear information.
Endoscopy: Upper endoscopy (esophagogastroduodenoscopy or EGD) and lower endoscopy (colonoscopy) can be used to directly visualize GISTs in the stomach or intestines.
Biopsy: While a biopsy is not always necessary for diagnosis, it may be performed to confirm the presence of a GIST and to identify specific mutations in the KIT or PDGFRA genes. Biopsy methods can include fine-needle aspiration (FNA) or core needle biopsy.
Endoscopic Ultrasound (EUS): EUS combines endoscopy and ultrasound to assess the size, location, and characteristics of GISTs within the gastrointestinal wall. It can help guide biopsies if needed.
Immunohistochemistry: After surgical removal of the tumor or biopsy, immunohistochemistry is used to analyze tissue samples for the presence of KIT and PDGFRA mutations. Positive staining for these markers supports the diagnosis of GIST.
Genetic Testing: Genetic testing can confirm the presence of specific mutations in the KIT or PDGFRA genes, which are characteristic of GISTs.
Once a GIST is diagnosed, its risk category and potential for metastasis are assessed based on various factors, including tumor size, location, mitotic rate (how rapidly cells are dividing), and presence of certain genetic mutations. This information helps guide treatment decisions, including whether surgery, targeted therapy (e.g., imatinib), or other approaches are necessary to manage the tumor. Early detection and appropriate management are crucial for improving the outcomes of individuals with GISTs.