FLOW-CYTOMETRIC ANALYSIS OF DNA PLOIDY IN 20 CASES OF SMOOTH-MUSCLE TUMOR OF GASTRODUODENAL ORIGIN

DNA ploidy was studied with flow cytometry in 20 cases of smooth-muscle tumor of gastroduodenal origin. There were 13 leiomyomas and 7 leiomyosarcomas. Clinico-pathological parameters, mitotic index, cellularity and histological grade clearly differed between leiomyoma and leiomyosarcoma. Only one of 13 cases of gastric leiomyoma revealed aneuploidy and the rest of 12 cases did diploidy. Conversely, 4 of 5 cases of gastric leiomyosarcoma showed aneuploidy. Two cases of duodenal leiomyosarcoma showed diploidy. Repeated measurements of DNA ploidy did not always yield the same ploidy as seen in the previous measurement, in that unhomogenous presence of DNA was inferred. Occurrence of aneuploidy was significantly higher in the leiomyosarcomas, but the prognostic value is still unlear, because postoperative late death occurred only in one case in which complete resection of widespread invasion was unsuccessful. Long-term follow-up is needed to evaluate the usefulness of DNA ploidy analysis as a prognostic factor of gastroduodenal smooth-muscle tumors.