CD117DOG1

CD117 and DOG1 are immunohistochemical markers used in the diagnosis of gastrointestinal stromal tumors (GIST). CD117 refers to the KIT proto-oncogene receptor tyrosine kinase, detected on tumor cells by specific antibodies; DOG1, standing for Discovered on GIST-1, is the protein product of the ANO1 gene (anoctamin-1).

CD117 (KIT) is a transmembrane tyrosine kinase receptor expressed in interstitial cells of Cajal and other tissues; in GISTs it is frequently expressed at high levels, and KIT signaling drives tumor cell proliferation. Most GISTs are KIT-positive (CD117-positive), and KIT status informs use of KIT-targeted therapies such as imatinib.

DOG1 (ANO1) encodes a calcium-activated chloride channel. DOG1 is a highly sensitive and relatively specific marker for GIST; most GISTs show strong DOG1 staining, including many KIT-negative tumors. However, DOG1 expression is not exclusive to GIST and can be seen in other tumors, so DOG1 positivity should be interpreted with morphology and other markers.

Diagnostic use: Pathologists typically perform immunohistochemistry for both CD117 and DOG1 when GIST is in the differential. A KIT-positive or DOG1-positive tumor with supporting morphology supports a GIST diagnosis; if both are negative, alternate diagnoses and genetic testing for KIT and PDGFRA mutations may be pursued.

Related clinical context: GISTs commonly harbor mutations in KIT or PDGFRA, which guide prognosis and therapy. Imatinib and other tyrosine kinase inhibitors remain central to management for advanced, unresectable, or metastatic cases, with DOG1 and CD117 helping confirm diagnosis across diverse presentations.