Gastrointestinal stromal tumour (GIST) is a rare but most common mesenchymal tumour in the gastrointestinal tract. Although GIST research has been carried out extensively worldwide, it has yet to be studied in Malaysia. To establish the immunohistochemical expression pattern of CD117 (c-KIT), CD34, S-100 and Desmin, the incidence of c-KIT and PDGFRA genes mutation in GISTs, and correlate it with clinicopathological parameters. Eleven clinically diagnosed GISTs were stained for CD117, CD34, Desmin and S-100 protein by immunohistochemical technique, and c-KITand PDGFRA gene mutations were studied by PCR-CSGE-DNA sequencing method. All GISTs (7 cases) stain positive for CD117, and co-expressed CD34. None of these cases express Desmin, and only one expressed S-100 protein focally. Fifty-seven percent (4/7 cases) of GIST harboured mutations at exon 11 of c-KIT gene, and they were all high risk and malignant cases. No mutation was detected at exons 9, 13 and 17 of KIT gene, and exons 12 and 18 of PDGFRA gene. Immunohistochemistry using a panel of antibodies shows consistent pattern of CD117 and CD34 expression in GIST, and mutational study may be a useful prognostic marker for kinase inhibitor treatment of GIST.
Introduction: Gastrointestinal stromal tumour (GIST) is relatively rare. The clinical behaviour of GIST ranges
from benign to frank sarcoma. The diagnosis is established through histopathological examination and
immunohistochemistry profile. In Malaysia, the number of publications related to GIST is relatively rare. This
study was therefore conducted to examine the demographic, histopathological and immunohistochemical
features of GIST cases diagnosed in the Department of Pathology, Hospital Tengku Ampuan Afzan, Kuantan,
Pahang from 2009 until 2014. Methods: Past histopathological records were reviewed. Demographic and
histopathological and immunohistochemical data of patients diagnosed were collected. Results: There were
28 cases (14 males and 14 females) diagnosed as GIST. Mean age was 56.4 years, and the majority were
above 40 years of age (85.7%). Stomach was the most common location (42.9%), followed by small intestine
(28.6%). In 23 cases (82%), the tumours exhibited spindle cell morphology, while epithelioid cell and mixed
cell types were seen in 3 cases (11%) and 2 cases (7%), respectively. Five cases were categorised as very low
risk to low risk behaviour, while 18 cases were intermediate to high. None of the histological parameters
analysed which include tumour morphology, necrosis, haemorrhage, nuclear atypia and mean number of
mitoses showed significance difference between the different risk behaviour groups. Positivity with KIT
(CD117), considered to be the defining immunohistochemistry feature, was negative in 2 cases. Conclusion:
Although this study is a retrospective study, the findings contribute to the knowledge on GISTS in Malaysia.
Future research related to GISTs in Malaysia should focus on molecular analyses for KIT and PDGFRA
mutations for diagnostic confirmation especially in KIT-negative cases and also for the purpose of
therapeutic response correlations.