(A) Stomach tumour ? GIST: A nodular tumour 140 x 135 x 115mm. The serosal
surface is irregular with a small amount of gastric mucosa attached at one edge
50 x 40 x up to 6mm thick. There are disruption in the capsule that appear
consistent with removal of adhesions but there is one irregular area 35 x 25mm
where the tumour appears to become adherent to brown tissue. The tumour is
partly necrotic with haemorrhagic material in the centre. There is a rim of
viable tumour at the periphery of the lesion up to 20mm thick.
Representative section A1-A6. A1-A2: viable areas of tumour. A3-A4: gastric
mucosa attached. A5: adhesion. A6: tumour.
A spindle cell growth, with striking nuclear palisading. In certain areas the
spindle cell palisades appear to be oriented around a central blood vessel. The
spindle cells otherwise form nests and fascicles. The spindle cells possess
delicate cytoplasmic processes, most evident in areas of oedema. The growth is
accompanied by a rich vasculature, many vessels thrombosed, and multiple areas
of necrosis or haemorrhage in various stages of organisation. The tumour is seen
to have expanded subserosally, with fibrous adhesion of spleen (slide A5). Fatty
tissue is also attached to the outer gastric surface. Little inflammation is
seen in the gastric mucosa. 10 - 15 mitotic figures per 50 high power fields are
seen in the tumour.
Immunohistochemistry (block A6):
ckit: intense cytoplasmic expression, including paranuclear accentuation of the
Gastrointestinal stromal tumour. According to tumour size and mitotic rate, the
expected chance of recurrence is high