Ovarian Cyst

Follicle: Normal physiologic cyst < 1 cm in diameter

• Dominant follicle may measure up to 3 cm

Functional cysts: Can measure up to 3-10 cm

• Corpus luteal cyst: Dominant follicle after ovulation

• Follicular cyst: Normal mature follicle fails to involute

Hemorrhagic cyst: Hemorrhage into functional cyst

US mainstay of ovarian imaging; MR in limited circumstances

Well-marginated round or ovoid structure within borders of ovary & having no solid component

• Thin wall (< 3 mm)

• No internal septa, nodule, fat, Ca²⁺, or vascularity

• ↑ heterogeneity with hemorrhage: Internal reticulations (or lace-like pattern) of clot mixed with tiny cystic spaces vs. layering debris

Usually asymptomatic; pain if large or complicated by rupture, hemorrhage, or torsion

Treatment/prognosis

• > 90% of all functional cysts resolve spontaneously

• Cysts < 3 cm should be considered physiologic in pre- & postmenarchal children

• Cysts up to 4-5 cm usually monitored with surveillance US

• Surgery vs. further imaging considered in larger cysts due to risk of torsion or neoplasm

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    For resection, ovarian-sparing approach preferred if benign etiology suspected

With complex ovarian cystic lesion in child, must consider: Could this be torsion, neoplasm, or other pathology

Low threshold for follow-up US of asymptomatic cyst in 4-6 weeks if initial study unclear (due to size or mild complexity)