Non-neoplastic ovarian cysts and polycystic ovaries
- Lesion
Most ovarian cysts are leftovers of the normal cycle and go away. Polycystic ovaries are a sign of a hormonal syndrome, not a tumour.
What it is
The ovary forms a follicle and a corpus luteum every cycle, and either can persist as a functional cyst. Follicle and luteal cysts are common, usually resolve, and matter when they bleed, rupture or twist. Polycystic ovaries, with many subcortical cysts under a thick capsule, are the ovarian picture of polycystic ovary syndrome, a disorder of anovulation, androgen excess and insulin resistance. Stromal hyperthecosis is a related, usually postmenopausal, form of androgen excess from luteinised stromal cells.
Structure
- Follicle cysts are usually small, thin-walled and multiple.
- Luteal cysts have a convoluted yellow wall and may contain blood clot.
- Polycystic ovaries: a pearly thick capsule over a string of cysts in the cortex; the stroma is often increased.
- Hyperthecosis: nodules of cells with lipid-rich cytoplasm scattered in a hyperplastic stroma.
Step by step
- In polycystic ovary syndrome, LH is high relative to FSH and insulin resistance raises insulin.
- LH and insulin drive the theca cells to make androgens.
- Excess androgens and too little FSH stop follicles from maturing, so many small follicles arrest as cysts and no corpus luteum forms.
- Without ovulation there is no progesterone; estrogen from converted androgens acts unopposed on the endometrium.
- Results: irregular periods, hirsutism and acne, infertility, endometrial hyperplasia and metabolic disease.
Clinical notes
- Functional cysts may cause pain, haemorrhage or torsion; most resolve over a few cycles.
- Polycystic ovary syndrome is the most common cause of anovulatory infertility; its diagnosis is clinical and hormonal, not just ultrasound.
- Virilisation that begins late or progresses rapidly suggests hyperthecosis or an androgen-secreting tumour.
Test yourself
Think of the answer, then tap the question to see it.
What do polycystic ovaries look like?
Enlarged with a thick white capsule and many subcortical follicle cysts with hyperplastic luteinised theca interna, and no corpora lutea.
What produces theca lutein cysts?
Very high hCG, as in molar pregnancy, multiple pregnancy or ovarian stimulation.
Why does polycystic ovary syndrome raise the risk of endometrial carcinoma?
Chronic anovulation leaves the endometrium exposed to estrogen without progesterone, causing hyperplasia and carcinoma.
Elsewhere in DurgiPedia
- Ovary: follicles, ovulation and corpus luteum
- Ovarian cycle, ovulation and the corpus luteum
- The menstrual cycle: ovary and endometrium
- Steroid hormone synthesis (overview)
Connections
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Ovarian Cyst (StatPearls (NCBI Bookshelf), 2026); Polyendocrine Metabolic Ovarian Syndrome (StatPearls (NCBI Bookshelf), 2026); Polycystic ovary syndrome: MedlinePlus Genetics (MedlinePlus, US National Library of Medicine, 2026).
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Representative model, for educational purposes only.