Morphologic Changes in the Endometrium Associated With the Use of the Mirena Coil: A Retrospective Study of 106 Cases

This study outlines the histologic changes seen in 106 endometrial specimens after use of the Mirena coil (levonorgestrel) and compares these changes with previous studies. The variables assessed include nature of the endometrial glands, metaplastic glandular changes, nuclear atypia, hobnail change, and endometrial hyperplasia. Stromal changes include pseudodecidualization, mucinous change, ulceration, and infiltration by granulocytes, neutrophils, and plasma cells, and stromal hyaline nodules, a feature not described previously. Additional changes include superficial micropapillary change, infarcted decidua, dystrophic calcification, hemosiderophages, polypoid indentations, cervical microglandular hyperplasia and endocervical pseudodecidualization. These variables are compared with a similar previous study. Significant differences in the incidence of glandular metaplasia, dystrophic calcification, plasma cell infiltrates, hemosiderophages, and presence of nuclear atypia are noted. With increased use of the Mirena coil, histopathologists need to be aware of the characteristic and constant endometrial changes due to progestogenic and mechanical effects, despite a wide variation in the duration of usage.