Immunophenotyping of gastrointestinal mesenchymal tumours in Lagos, Nigeria.

BACKGROUND: Gastrointestinal stromal tumour (GIST) represents only 1% of all malignant tumours of the gastrointestinal tract (GIT) but it is the most common gastro-intestinal mesenchymal tumour (GMT) with majority arising from the stomach and small intestine. OBJECTIVE: To determine the prevalence of GIST using immunophenotypic characteristics. METHODS: Materials were formalin fixed paraffin embedded blocks of GMT diagnosed in Lagos Nigeria between January 1995 and February 2007. Sections were stained with CD117, CD34, SMA, S100 and Desmin antibodies at the research Laboratory of The Leeds General Infirmary, United Kingdom following standard procedure. RESULTS: Thirty-two cases of GMT (aged 10 to 78 years with a mean age of 46 and M: F=1.3:1) were analyzed. GIST accounted for 13 (40.6%), smooth muscle tumours 7(22%), vascular three(9.3%), de-differentiated liposarcoma two (6.2%), and unclassified (3%) of the GMT cases. Immuno-staining was not done for six cases of lipoma (18.7%). GIST patients had a mean age of 45.4 years with a M: F of 1.6:1; 54% was located in the stomach. Histologically, spindle cell type predominated accounting for 46% followed by mixed (31%) and epithelioid types (23%). Only 30.7% the GIST were suspected before immuno-staining. CONCLUSION: Gastrointestinal stromal tumour is the most common gastro-intestinal mesenchymal tumour in Lagos with a male preponderance. The most common site is the stomach. The immunophenotypic characteristics are comparable with gastrointestinal stromal tumours reported from other parts of the world.