Deciduosis of the appendix. Differential diagnosis of acute appendicitis

Deciduosis of the appendix is a rare cause of acute appendicitis in pregnan cy. Ectopic decidual cells localized in the submesothelial stroma may repre sent a physiologic reaction of the pluripotent stromal cells to progestatio nal hormonal stimulation. Less frequently, deciduosis is based on a preexis ting extragenital endometriosis, visible in a localization other than stric tly submesothelial, in residuals of cyclic proliferation and bleeding, and in endometrial glandular formations embedded in the decidual cells.