From the Guidelines
CD117 positive cells in gastric tissue primarily indicate the presence of gastrointestinal stromal tumors (GISTs), which are the most common mesenchymal tumors of the gastrointestinal tract, as supported by the most recent guidelines from the British Sarcoma Group 1. The presence of CD117 positive cells is a key diagnostic marker for GISTs, with approximately 95% of GISTs expressing CD117 1. The intensity and pattern of CD117 staining can help determine the nature of the lesion, with GISTs typically showing membranous and cytoplasmic staining. This marker is crucial for distinguishing GISTs from other spindle cell tumors of the stomach such as leiomyomas, schwannomas, or leiomyosarcomas, which are typically CD117 negative. Some key points to consider when evaluating CD117 positive cells in gastric tissue include:
- The diagnosis of GIST relies on morphological assessment and immunohistochemistry (IHC), with CD117 and/or DOG1 immunopositivity supporting the diagnosis 1.
- Molecular analysis for typical variants in KIT or PDGFRA may help confirm the diagnosis, especially in CD117 and/or DOG1 immunonegative suspected GIST 1.
- The mitotic count has prognostic value and is more accurate and reproducible when expressed as the number of mitoses in a total area of 5 mm2 1. Identification of CD117 positive cells is important for treatment decisions, as GISTs may respond to targeted therapies like imatinib mesylate that inhibit the c-kit tyrosine kinase 1.
From the Research
CD117 Positive Cells in Gastric Tissue
- CD117 positive cells in gastric tissue are indicative of gastrointestinal stromal tumors (GISTs) 2, 3, 4, 5, 6.
- GISTs are rare neoplasms of the gastrointestinal tract associated with high rates of malignant transformation 2.
- CD117 is a sensitive marker for GISTs and is more specific than CD34 6.
- Most GISTs present asymptomatically and are best identified by computed tomography (CT) scan 2.
- The presence of CD117 positive cells is a key factor in the diagnosis of GISTs, as it is expressed in subsets of hematopoietic stem cells, mast cells, melanocytes, and interstitial cells of Cajal of the GI tract 4, 6.
Diagnosis and Management
- The accurate diagnosis of GISTs is important, as specific chemotherapeutic agents are now available for their management 5.
- CD117 positive GISTs are ideal candidates for treatment with molecularly targeted specific chemotherapeutic agents, such as imatinib 5.
- Histologically diagnosed stromal tumors of the gut should be subjected to immunostain for CD117 to provide specific medical management and prevent recurrence and metastasis 5.
Characteristics of GISTs
- GISTs are biologically distinct and heterogeneous group of tumors of the gut, arising from interstitial cells of Cajal in the gut wall 4, 5.
- The tumor results from mutation of the c-kit gene, which codes for CD117 containing tyrosine kinase receptor of Cajal cells 5.
- GISTs can be benign or malignant, and their malignant potential can only be determined by surgical resection and histologic evaluation 3.