Researchers described the case of a 71-year-old male who was diagnosed with a gastrointestinal stromal tumor (GIST) with 10% of the tumor cells showing positive staining for Ki-67, as published in Cureus.

Previous studies have shown that Ki-67 expression greater than 8%-10% suggests a high risk of recurrence of GIST and may compromise the efficacy of therapy.

“Given the limited but significant Ki-67 data, future studies should focus on Ki-67’s importance in determining prognosis as Ki-67 provides a reliable and reproducible approach to assess prognosis,” the authors wrote.

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At clinical admission, the patient complained of bloody diarrhea for 2 days, with associated nausea, vomiting, and abdominal cramping. Computed tomography of the abdomen and pelvis showed a large solid mass with cystic components, which was not observed with esophagogastroduodenoscopy or colonoscopy.

Read more about GIST symptoms

The patient underwent surgery to remove a tumor in the ileum (14 cm x 11.5 cm x 10 cm). The diagnosis of GIST was confirmed by immunohistochemical analysis of the specimen. The tumor was high grade with a high mitotic rate at 30 mitoses/50 high-power fields, spindle cell morphology, and diffuse CD117/c-Kit protein expression.

“Morphological features and immunohistochemistry alone are not enough to make the diagnosis of GIST and must coincide (ie, the tumor must be KIT+ and have spindle cell morphology; however, one or the other is not sufficient for diagnosis),” the authors explained.

Predicting Prognosis in Patients With GIST

The diagnosis of GIST must include the identification of overexpressed KIT/CD117. Ki-67 is a proliferation marker that showed a strong correlation with the mitotic index. It has been used as an important immunocytochemical marker for several tumors.


Kadado KJ, Abernathy OL, Salyers WJ, Kallail KJ. Gastrointestinal stromal tumor and Ki-67 as a prognostic indicator. Cureus. Published online January 1, 2022. doi:10.7759/cureus.20868