Uterine leiomyoma

Uterine leiomyomas, also referred 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. There are various medical, surgical and interventional treatment options.

They occur in ~25% of women of reproductive age 1 and are particularly common in the African population.

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.

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:

  • hyaline degeneration: focal or generalized hyalinisation: this is the most common type of degeneration (can occur in ~60% of cases) 6
  • cystic degeneration: ~5%
  • myxoid degeneration: generally considered uncommon although reported as high as 50% by some authors 14
  • red/carneous degeneration: due to hemorrhagic infarction, which can occur particularly during pregnancy, and may present with acute abdominal pain

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 are 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
    • 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 is considered. It is also of great value in differentiating a pedunculated fibroid from an adnexal mass 5.

Common treatment options include:

  • rarely invasion of adjacent venous channels leading to intravenous leiomyomatosis 15
  • rarely (0.1-0.5%), they undergo malignant degeneration into leiomyosarcomas
  • in extremely rare instances, lesions capable of metastasizing without malignant transformation: benign metastasizing leiomyoma 3
  • fibroids may torse, leading to acute pelvic pain
  • pregnancy may cause fibroid growth in 30%

General imaging differential considerations include:

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

Ultrasound - gynaecology
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Article information

rID: 10915
System: Gynaecology
Synonyms or Alternate Spellings:
  • Uterine fibroid
  • Uterine fibroma
  • Fibroid disease
  • Fibroids
  • Uterine fibroids
  • Uterine leiomyomas
  • Uterine leiomyomata

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Cases and figures

  • Figure 1: surgical specimen
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  • Case 1: on angiogram
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  • Figure 2: classification system
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  • T2 annotated

E -...
    Case 2: annotated as F
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  • T1 FS annotated

    Case 2: annotated as F
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  • Case 3: calcified uterine fibroid
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  • Incidental uterin...
    Case 4
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  •  Case 5
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  • Case 6: prolapsing uterine leiomyoma
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  • Case 7: broad ligament leiomyoma
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  • Case 8
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  • Case 9: sub mucosal leiomyoma on HSG
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  • Uterine leiomyomas
    Case 10
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  • Case 11
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  • Subserosal uterin...
    Case 12: large sub-serosal leiomyoma
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  • Case 13: giant calcific uterine leiomyoma
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  • Case 14
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  • Case 15: giant leiomyoma
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  • Case 16
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  • Selective angiogr...
    Case 17: embolization
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  • Case 18
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  • Case 19: with concurrent adenomyosis
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  • Case 20: calcified fibroid
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  • Case 21: calcified fibroid
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  • CT scout view
    Case 22
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  • Case 23: with IUCD
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  • Case 24: with red degeneration in pregnancy
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  • Case 25: large bilobed
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  • Case 26: with degeneration
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  • Intra-mural uteri...
    Case 27: intra-mural uterine leiomyoma
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  • Case 28
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  • Case 29
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  • Case 30: Calcified fibroid
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  • Case 31: multiple uterine leiomyomas
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