Probably not a rare condition.
Depending on the “look” and the size gynaecologists will advise their patients.
Many smaller cysts disappear spontaneously.
I don’t want to write about this “not my field” issue but about my experience as described below.
I “publish” here for the first time my experience with probably tens of cases for at least the last 35 years.
The homeopathic formule I used is from a German homeopath Dr.med.Emil Rehm [Bewaehrte homoopatische Rezepte page 60 [Ovarialtumor][may he be blessed]

Paladium /Platinun/ Conium/ Apis / Bufo, all as d30 [or D6 sometimes] and if the cyst was only at the left side I added Lachesis [my own addition
In virtually all cases I have seen a regression from the tumour [US confirmatiom]and disappearance to my own surprise! Some of the cysts were diagnosed by gynaecologists as extremely suspicious of a malignant tumour.
I asked the patients if they were willing to wait 4-6 weeks before considering an operation in light of my experience.
The most REMARKABLE thing I have seen [and I don’t blame any doctor if he does not believe this!] is the disappearance of a big hamartoma ovary cyst [you can look this up on Google]
I hope that some of my colleagues are willing to try this formula and write to me about their experiences..