Theca lutein cyst

A theca lutein cyst (TLC) also known under the condition hyperreactio luteinalis (HL) is a type of functional ovarian cyst. They are typically multiple and bilateral.

Pathology

They are thought to originate due to excessive amounts of circulating gonadotrophins such as beta-HCG. Hyperplasia of the theca interna cells is the predominant characteristic on histology. The ovarian parenchyma is often markedly oedematous and frequently contains foci of luteinized stromal cells.

Associations

• they have a very high association with gestational trohpoblastic disease.

Other reported associations include:

• multifetal pregnancy ⁴
• ovarian hyperstimulation syndrome (OHSS) ⁴
• rarely -
  • pregnancy with background chronic renal failure ²
  • normal uncomplicated pregnancy ⁵

Radiographic features

The clinical context is vital in correct imaging interpretation.

General

The cysts are usually large (~ 2-3 cm) and have a typical multilocular cystic appearance across all imaging techniques ⁴.

Ultrasound

Bilateral enlarged, multicystic ovaries. The cysts are classically thin walled and have clear contents. There is large amount of solid component which is possibly the residual ovarian stroma.

MRI

Typically seen as bilateral (occasionally unilateral) ovarian enlargement with multiple cysts which are of generally of uniform size.

The residual parenchyma within the enlarged ovaries have been reported to show ⁶

• T1 C+ (Gd) - intense contrast enhancement
• T2 - intermediate signal intensity
• DWI - high signal 

Natural course

Following evacuation of a molar pregnancy, the associated theca lutein cysts resolve by ~ 2-4 months.

There are cases reported of nomal pregnancies associated with hyperreactio leutinalis which have resolved gradually post delivery.

Surgical emergency if ovarian torsion occurs.

Differential diagnosis

For large multiple bilateral ovarian cysts consider

• ovarian hyperstimulation syndrome - can also be an association
  • often has a history of ovulation induction
  • may have free pelvic fluid
• mucinous ovarian malignancy 
  • a more solid component may be present noted
  • ovarian tumour markers +/- Beta HCG levels may be elevated ^{ref required}

See also

• ovarian cysts