Pitfalls in the diagnosis of endometriosis: a condition characterized by a plethora of unusual histological features

The histological diagnosis of endometriosis is usually straightforward. However, for a large number of reasons, there may be diagnostic difficulties. These difficulties may be related to both unusual morphological features in endometriosis and the occurrence of endometriosis at unusual sites. In this review, 10 problematic areas in the histological diagnosis of endometriosis are discussed.