Gastrointestinal stromal tumour
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The gastrointestinal stromal tumour, abbreviated GIST, is uncommon tumour of the GI tract.
General
Epi.
- arises from Interstitial cells of Cajal[1]
- Classically splits the layers of the muscularis propria - as this is where the interstitial cells of Cajal are located.[2]
Factors predictive of malignant behaviour[1]
- Large size.
- Often benign if small size.
- High mitotic rate (for area 5mm^2).
- Site - small intestine GISTs worse than stomach GISTs.
Small intestine bad prognosis:[1]
- >5 mitoses/5 mm^2 or size >10 cm.
Stomach bad prognosis:[1]
- >5 mitoses/5 mm^2 and size >5 cm.
Location
Most common locations in order:[1]
- 60% in stomach.
- 35% in small intestine.
- 5% elsewhere.
Small intestinal GISTs have a worse prognosis than gastric ones.[1]
Definition
- Mutation in the Kit gene or PDGFRA (Platelet-derived growth factor receptor, alpha polypeptide) gene.[1]
Micro.
- Classically, spindle cell morphology; however, may be epithelioid (round).
- +/-Cytoplasmic inclusions.[3]
IHC
- Desmin+ in 5%.[1]
ICH Work-up panel
- S-100 (neural tumours, rarely +ve in GISTs[1]).
- CD34, CD117 (GIST).
- Desmin (muscle tumours).
DDx
- Leiomyosarcoma.
- Leiomyoma.
- Neural tumours.
- Neurofibroma.
- Schwannoma (GFAP+ --uniformly neg. in GISTs).[1]
Special tests
- Sequence Kit gene, PDGFRA gene.
- Kit gene sequencing is being done more frequently as of late-- if a mutation is found it suggest the drug imatinib will be effective.
Treatment
- Imatinib (Gleevec) - drug was developed for chronic myelogenous leukemia.
- There are other similar drugs, e.g. nilotinib and dasatinib.
See also
References
- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 Miettinen M, Lasota J (October 2006). "Gastrointestinal stromal tumors: review on morphology, molecular pathology, prognosis, and differential diagnosis". Arch. Pathol. Lab. Med. 130 (10): 1466–78. PMID 17090188. http://journals.allenpress.com/jrnlserv/?request=get-abstract&issn=0003-9985&volume=130&page=1466.
- ↑ Agaimy A, Wünsch PH (August 2006). "Gastrointestinal stromal tumours: a regular origin in the muscularis propria, but an extremely diverse gross presentation. A review of 200 cases to critically re-evaluate the concept of so-called extra-gastrointestinal stromal tumours". Langenbecks Arch Surg 391 (4): 322–9. doi:10.1007/s00423-005-0005-5. PMID 16402273.
- ↑ PMID 775795