Morphological Features of Metastatic Gastrointestinal Stromal Tumors after Gleevec Treatment: Two Cases Report

ABSTRACT

We report two patients with metastatic gastrointestinal stromal tumors (GISTs) with a focus on the morphological features related to Gleevec treatment. In case 1, a 50-year-old woman presented with a 1.8 cm metastatic GIST in the liver after resection of a gastric GIST. Majority of the metastatic tumor showed fibrosis and hyalinization after 8 weeks of Gleevec treatment. CD117-positive cells were present in approximately 1% of the overall tumor. In case 2, a 2 cm and 14 cm metastatic liver masses were found in a 54-year-old man who had a rectal GIST. After 4 weeks of Gleevec treatment, metastatic tumors showed a decrease in size on CT scan. The metastatic tumors showed a decrease in number of tumor cells. The hemorrhage, cystic changes, necrosis, and fibrosis made up approximately 90% of the tumor. The morphological features related to Gleevec treatment are important for correct diagnosis and evaluation of tumor response and prognosis.