The aim of the study was to evaluate the incidence of the reactions for
vimentin and
desmin in gastric
leiomyomas routinely processed in
formalin and embedded i
paraffin. The material studied included four benign
leiomyomas, seven malignant
leiomyomas and three malignant
epithelioid leiomyomas. A positive reaction to
vimentin was found in 13 out 14
leiomyomas under study. The number of neoplastic cells showing
vimentin expression was larger in malignant, especially
epithelioid leiomyomas than in non-malignant
leiomyomas. A positive reaction for
desmin in neoplastic cells was found in 9
leiomyomas 64%. One non-malignant
leiomyoma showed a moderate reaction. In the remaining eight cases the reaction was weak and occurred in single neoplastic cells. Coexpression of
vimentin and
desmin in neoplastic cells occurred in 8 out of 9
leiomyomas with a positive reaction for
desmin. Coexpression of
vimentin and
desmin occurred also in the smooth muscle cells of blood vessels in all 14 cases. A weak reaction for
desmin or its lack in the tumour cells of
leiomyomas with its marked expression in the smooth muscle cells of the blood vessels and gastric wall outside the
tumor points rather to a small number of
desmin filaments in the neoplastic cells than to their destruction by fixation in
formalin. The occurrence of the reaction to
desmin only in a limited number of neoplastic cells questions the reliability of its use in the oligopiopsy material.