We report nine cases of uterine leiomyomas with an average of more tha
n 10 mast cells per high-power field. The clinical presentation and mo
rphological features of the tumors did not differ from those of conven
tional leiomyomas. Two cases also showed eosinophilia. The adjacent my
ometrium did not show an increased number of mast cells. Mast cells ar
e frequently numerous in leiomyomas, but the significance of this find
ing is unknown.