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Gastrointestinal stromal tumours
M Miettinen1, M Sarlomo-Rikala, J Lasota
1Department of Soft Tissue Pathology, Armed Forces Institute of Pathology, Washington, DC, USA.
Annales Chirurgiae Et Gynaecologiae
|January 19, 1999
Summary
Gastrointestinal stromal tumours (GISTs) are distinct mesenchymal neoplasms. They are characterized by unique features and are most common in the stomach and small intestine.
Area of Science:
- Gastroenterology
- Oncology
- Pathology
Background:
- Gastrointestinal stromal tumours (GISTs) are the most common mesenchymal neoplasms of the GI tract.
- Traditionally misclassified, GISTs possess unique histological, immunophenotypic, and molecular genetic profiles.
- They primarily affect individuals over 40, with benign forms significantly outnumbering malignant ones (10:1).
Purpose of the Study:
- To delineate the distinct characteristics of GISTs.
- To differentiate GISTs from other smooth muscle tumours and schwannomas.
- To establish criteria for evaluating GIST malignancy.
Main Methods:
- Histological examination for spindle cell or epithelioid patterns.
- Immunohistochemical analysis for CD34 and c-kit (CD117) expression.
- Genetic analysis for DNA losses (14q) and c-kit mutations.
Main Results:
- GISTs exhibit unique histology, immunophenotype (CD34+, c-kit+), and genetics (14q loss, c-kit mutations).
- Most GISTs occur in the stomach (60-70%) and small intestine (30%).
- Malignancy is assessed by mitotic count, tumour size, and spread; high counts (>5/10 HPF) or large size (>10 cm) indicate significant risk.
Conclusions:
- GISTs are a distinct entity separate from leiomyomas, characterized by c-kit expression and specific genetic alterations.
- Accurate diagnosis relies on integrated histological, immunohistochemical, and genetic findings.
- Tumour size, mitotic activity, and extragastric spread are crucial for predicting GIST behavior and guiding treatment.