Page views in 2023: 5
Page views in 2024 to date: 9
11 January 2006 - Case #33

All cases are archived on our website. To view them sorted by case number, diagnosis or category, visit our main Case of the Month page. To subscribe or unsubscribe to Case of the Month or our other email lists, click here.

This case was contributed by Dr. Michael Constantinescu, Armstrong County Memorial Hospital, Kittanning, Pennsylvania, USA.


Website news:

Visit and follow our Blog to see recent updates to the website.


Case #33

Clinical history:
A 48 year old man with GI symptoms was discovered to have a 4 cm stomach tumor.

Microscopic images (low to high power):



What is your diagnosis?

Click here for diagnosis and discussion:


Diagnosis: Gastrointestinal stromal tumor (GIST) of stomach

Immunostain images:
CD117, low power

CD117, low power

CD117, high power

CD117, high power



Discussion:
In 1983, Mazur and Clark suggested that GIST tumors, once thought to be derived from smooth muscle, might have a neural origin (Am J Surg Pathol 1983;7:507). Subsequent work has demonstrated that these tumors differentiate along the lines of the interstitial cell of Cajal, involved in the gut pacemarker activity that regulates peristalsis.

67% of all GIST tumors arise in the stomach, where their behavior is usually benign. In the stomach, poor prognostic factors are location in the fundus or GE junction, coagulative necrosis, ulceration and mucosal invasion (Am J Surg Pathol 2005;29:52). Morphology for tumors from various sites has also been used to predict behavior, with pure or mixed cellular spindle cell or epithelioid cell patterns associated with benign behavior and other patterns considered not to be benign (Am J Surg Pathol 2002;26:705).

These tumors are immunoreactive for CD117 / KIT, as well as CD34 (Hum Pathol 2002;33:669). Of note, the interstitial cell of Cajal is also CD117+ and CD34+.

A novel therapy for metastatic or unresectable CD117+ GIST tumors, as well as CML and other CD117+ tumors, is STI-571 (Gleevec, imatinib mesylate), an inhibitor of receptor tyrosine kinase. It inhibits constitutive activation of mutated KIT and confirmation of KIT immunoexpression is required for its use (Pathol Int 2006;56:1). In the present case, with no evidence of metastatic tumor, treatment consisted only of tumor excision.

Reference: Mod Pathol 2003;16:366


Image 01 Image 02