Uterine leiomyoma

Last revised by Dr Calum Worsley on 28 Sep 2022

Uterine leiomyomas, also known as uterine fibroids, are benign tumors of myometrial origin and are the most common solid benign uterine neoplasms. Commonly an incidental finding on imaging, they rarely cause a diagnostic dilemma.

They are clinically apparent in ~25% of women of reproductive age and over 70% of women by menopause 21. Fibroids are responsive to hormones (e.g. stimulated by estrogens). Being rare in prepubertal females, they commonly accelerate in growth during pregnancy and involute with menopause 1.

  • 2-3x increased incidence in Black women than in White women 20,21
  • increasing incidence with age: 10x more common in 41-60 years than 21-30 years, reaching a peak at 50-60 years 20,21
  • 3x increased incidence with a family history of uterine fibroids 21

They are often asymptomatic and discovered incidentally. Signs and symptoms associated with fibroids include:

  • abnormal vaginal bleeding
  • pain
  • infertility
  • palpable masses

Leiomyomas are benign monoclonal tumors 16 predominantly composed of smooth muscle cells with variable amounts of fibrous connective tissue. They are commonly multiple (~85% 8), and range significantly in size.

Fibroids may have a number of locations within or external to the uterus:

Subserosal fibroids may be pedunculated and predominantly extra-uterine, simulating an adnexal mass. Any fibroid may undergo atrophy, internal hemorrhage, fibrosis, and calcification.

They can also undergo several types of degeneration:

Popcorn calcification within the pelvis may suggest the diagnosis.

Ultrasound is used to diagnose the presence and monitor the growth of fibroids:

  • uncomplicated leiomyomas are usually hypoechoic, but can be isoechoic, or even hyperechoic compared to normal myometrium
  • calcification is seen as echogenic foci with shadowing
  • cystic areas of necrosis or degeneration may be seen
  • Venetian blind artifact may be seen but edge shadowing +/- dense posterior shadowing from calcification is also typically seen 17
  • fibroids are usually seen as soft tissue density lesions and may exhibit coarse peripheral or central calcification
  • they may distort the usually smooth uterine contour
  • enhancement pattern is variable

MRI is not generally required for diagnosis, except for complex or problem-solving cases. It is, however, the most accurate modality for detecting, localizing, and characterizing fibroids. Size, location, and signal intensity should be noted.

Signal characteristics are variable and include 1,2:

  • T1
    • non-degenerated fibroids and calcification appear as low to intermediate signal intensity compared with the normal myometrium
    • characteristic high signal intensity on T1 weighted images/an irregular, T1 hyperintense rim around a centrally located myoma suggests red degeneration, which is caused by venous thrombosis
  • T2
    • non-degenerated fibroids and calcification appear as low signal intensity
    • as they are usually hypervascular, flow voids are often observed around them 10
    • fibroids that have undergone cystic degeneration/necrosis can have a variable appearance, usually appearing high signal on T2 sequences
    • hyaline degeneration is demonstrated as low T2 signal intensity
    • cystic degeneration, which is an advanced stage of intratumoral edema, also shows high signal intensity on T2 weighted images and does not enhance 10
  • T1 C+ (Gd)
    • variable enhancement is seen with contrast administration
    • the marked high signal intensity with gradual enhancement (albeit mild) suggests myxoid degeneration

MRI is of significant value in the symptomatic patient when surgery and uterine salvage therapy are considered. It is also of great value in differentiating a pedunculated fibroid from an adnexal mass 5.

There are various medical, surgical, and interventional treatment options:

General imaging differential considerations include:

In occasional situations, it may be difficult to differentiate between uterine leiomyomas and:

ADVERTISEMENT: Supporters see fewer/no ads

Cases and figures

  • Figure 1: surgical specimen
    Drag here to reorder.
  • Case 1: on angiogram
    Drag here to reorder.
  • Case 2: annotated as F
    Drag here to reorder.
  • Case 2: annotated as F
    Drag here to reorder.
  • Case 3: calcified uterine fibroid
    Drag here to reorder.
  • Case 4
    Drag here to reorder.
  •  Case 5
    Drag here to reorder.
  • Case 6: prolapsing uterine leiomyoma
    Drag here to reorder.
  • Case 7: broad ligament leiomyoma
    Drag here to reorder.
  • Case 8
    Drag here to reorder.
  • Case 9: sub mucosal leiomyoma on HSG
    Drag here to reorder.
  • Case 10
    Drag here to reorder.
  • Case 11
    Drag here to reorder.
  • Case 12: large sub-serosal leiomyoma
    Drag here to reorder.
  • Case 13: giant calcific uterine leiomyoma
    Drag here to reorder.
  • Case 14
    Drag here to reorder.
  • Case 15: giant leiomyoma
    Drag here to reorder.
  • Case 16
    Drag here to reorder.
  • Case 17: embolization
    Drag here to reorder.
  • Case 18: with torsion
    Drag here to reorder.
  • Case 19: with concurrent adenomyosis
    Drag here to reorder.
  • Case 20: calcified fibroid
    Drag here to reorder.
  • Case 21: calcified fibroid
    Drag here to reorder.
  • Case 22
    Drag here to reorder.
  • Case 23: with IUCD
    Drag here to reorder.
  • Case 24: with red degeneration in pregnancy
    Drag here to reorder.
  • Case 25: large bilobed
    Drag here to reorder.
  • Case 26: with degeneration
    Drag here to reorder.
  • Case 27: pyoleiomyoma
    Drag here to reorder.
  • Case 28
    Drag here to reorder.
  • Case 29
    Drag here to reorder.
  • Case 30: calcified
    Drag here to reorder.
  • Case 31: multiple uterine leiomyomas
    Drag here to reorder.