GASTROINTESTINAL STROMAL TUMOURS.

The histogenesis of 10 spindle cell tumors of gastrointestinal tract (GIT) of last three years of our institution was studied, on the basis of immunohistochemical (IHC) staining. The tumours were categorized into benign, borderline malignant and malignant, mainly based on the histologic parameters (HP) such as predominant cell type, cellularity, type of growth pattern, mitotic figures etc. The study included 7 males and 3 females in the age group from 21 to 56 years. 4 tumors were located in stomach and 6 in the small intestine. The initial symptoms included pain abdomen, palpable mass and general weakness. There were 7 benign, 1 borderline and 2 malignant leiomyomatous tumors according to the histologic parameters we followed. Vimentin, desmin, S-100, and non-specific enolase (NSE) were the immunological markers used to identify the cellular lineage. Smooth muscle differentiation was demonstrated by nine (6 benign and 3 malignant) tumours. One male patient (Case 1), originally reported as leiomyoma based on HP, was positive for S-100 and NSE. Another case, a female, categorised as leiomyosarcoma, showed dual differentiation toward myogenic and neural elements on IHC staining (Case 2). IHC study played important role in the identification of cellular differentiation of these tumors as the same was not possible on light microscopic findings alone.