Dr. Lotus Alphonsus

So, for example, an endoscopic ultrasound or EUS is useful for biopsy and depth assessment.

An MRI, on the other hand, is preferred for rectal and pelvic gists.

And a PET scan might be useful in select cases when you're assessing response to treatment or therapy.

Remember that GIST can bleed intraluminally or intraperitoneally, so a patient with unexplained GI bleeding, particularly if it's intermittent or obscure, as in a patient with negative or normal scopes, really should trigger you to consider the small bowel GIST, and a referral for capsule endoscopy or CT enterography might be reasonable.

Finally, pathology is crucial.

A biopsy is often completed via that endoscopic ultrasound fine needle aspiration for gastric and rectal lesions.

Immunohistochemistry will typically reveal CD117, aka CKIT, and or DOG1, which are both sensitive and specific markers for diagnosing GIST.

The combination of both CD117 and DOG1 staining covers approximately 98% of GIST cases.

Of note, biopsies should be avoided in patients who are unstable or bleeding significantly.

Once the diagnosis is confirmed, always involve GI and oncology early.

GIST management is nuanced and multidisciplinary.

Next, we will be moving on to treatment.

Prognosis largely depends on the tumor size and mitotic activity.

So larger tumors and high mitotic counts have a greater risk of recurrence or metastasis.

We will separate treatment into localized resectable GIST and metastatic or unresectable GIST.

Remember, traditional chemotherapy and radiation are typically ineffective against GIST.

So for localized resectable GIST, surgical resection is first line.

Lymph node dissection is not necessary.

GISTs are typically not able to metastasize to lymph nodes.

So if a GI mass is associated with lymphadenopathy, you want to consider lymphoma, adenocarcinoma, or even neuroendocrine tumors.