Characterization of a population of unique granular lymphocytes in a bitch deciduoma, using a panel of histo- and immunohistochemical markers

The ovaries and uterus were collected after ovariohysterectomy from a 16-month-old Labrador bitch in diestrus that never mated. Discrete swellings were found in the uterine horns, with the macroscopic appearance of normal early pregnancy. At histologic examination, the endometrium, devoid of any conceptus and chorion, showed a marked proliferation, on the basis of which a diagnosis of deciduoma was made. A remarkable population of stromal eosinophilic granular lymphocytes was present, especially in the axis of the endometrial folds. Periodic acid–Schiff and Dolichos biflorus–lectin histochemical reaction and a panel of 10 immunohistochemical markers were used to characterize eosinophilic granular cells. Our findings allowed us to compare these granular cells with the granulated decidual cells, whose presence was until now described only in primates, rodents, or a few other epitheliochorial species. On the basis of our results, the importance of eosinophilic granular cells in a decidualization process is hypothesized to occur also in the bitch.