Patient went on to have a biopsy.
MICROSCOPIC DESCRIPTION
The sections show fragments of a tumour comprising spindle cells with plump, frequently cigar-shaped, nuclei, arranged in sweeping fascicles. There is moderate nuclear pleomorphism but only 1 mitosis per 50 high power fields. There are areas of haemorrhage within the tissue fragments (which may represent surgical artifact) and one fragment shows a single small focus of necrosis. The lesion contains a light, diffuse infiltrate of lymphocytes and plasma cells and in some areas there are a few neutrophils. Immunoperoxidase stains show that the tumour cells are positive for smooth muscle actin and negative for S-100 and c-Kit +ve.
FINAL DIAGNOSIS
Gastrointestinal stromal tumour of uncertain malignant potential showing smooth muscle differentiation.