Figure 1. Hysteroscopic aspect of osseous metaplasia of the endometrium.

Osseous metaplasia in the uterine cavity is a rare phenomenon arising from an unusual transformation of non-osseous connective tissue into mature bone. It is unclear how this alteration occurs and it has no single clinical manifestation. We report a case of asymptomatic endometrial osseous metaplasia of the isthmus with a singular picture: numerous long, floating bone-like structures in the cavity. The lesion was treated by operative hysteroscopy. Histological findings described a rare picture of true osseous metaplasia with the extraordinary presence of cells referable to areas of hematopoietic tissue in the cavities of trabecular bone. Physicians should be more informed and alert regarding this rare disorder in all its strange shapes and localizations, so as to be able to follow suitable therapy.