Leiomyoma of the sigmoid mesocolon associated to hemorrhagic infarct and high count of mast cells

Leiomyoma is a soft-tissue benign tumor and its occurrence in the mesocolon is extremely rare. We present a particular case of a leiomyoma of the sigmoid mesocolon of a 58-year-old man, associated to a hemorrhagic infarction treated surgically and without recurrences after 1 year of follow-up. The macroscopic, histopathologic, and immunohistochemical features are presented and discussed. The high mast cell count associated with a low rate of cell proliferation is a sign of the benign biological behavior in this entity and may be helpful hallmarks for the differential diagnosis with other gastroenterological neoplasia.