By I.Soussis MD

The reputable journal Human Reproduction Update in  2014 published an excellent study by ΑΜ Sanchez et al., on how an endometrioma ( a chocolate cyst) affects the surrounding healthy ovarian tissue. They reviewed the scientific literature of the last 25 years on the subject. They excluded all the clinical articles and they focused on what is known on basic science.

The endometrioma contains toxic substances such as free iron, free oxygen radicals, proteolytic enzymes and chemicals of inflammation in a concentration of tens and even hundreds of times higher, than those in blood or in non endometriotic benign cysts.

The concentration of CA-125 in the endometriotic cyst is 100 times higher than in the blood. The reason why this happens is unknown. It is however known that the CA-125 is a strong indicator of inflammation.

Toxic factors affect the endometriotic cells with which they come into contact. They may alter their gene expression or they can even cause genetic mutations.

The wall of the chocolate cyst is thin and consists of connective tissue and the cortex of the ovary.

Oxygen free radicals (which are powerful cellular stress factors), proteolytic enzymes and other toxic substances diffuse through the cyst wall to the adjacent healthy ovarian tissue. The healthy ovary is reacting with the creation of scar tissue, in an attempt to limit the damage.

The smooth muscle fibers in the region undergo metaplasia and the small vessels of the ovary also sustain damages . As a consequence of the vascular lesions, the follicles are not fed properly, they do not mature and finally they regress. Their numbers decrease.

Indeed many histological studies have shown reduced follicular density  in the ovary, in areas neighboring with ovarian endometriomas.

Now we believe that the damage of the ovary is more due to the action of these toxic agents, rather than the stretching of the tissues, caused by the cyst.

Knowledge of the pathophysiology can lead to the introduction of new drug therapies, that neutralize the action of these toxic agents. We could thus protect the ovary from damages caused by endometriosis.

The distinguishing cellular and molecular features of the endometriotic ovarian cyst: from pathophysiology to the potential endometrioma-mediated damage to the ovary A.M. Sanchez1, P. Viganò2,*, E. Somigliana3, P. Panina-Bordignon1, P. Vercellini3,4,5 and M. Candiani2 http://humupd.oxfordjournals.org/content/20/2/217.long