Case Id: JSSMCRADC0066

Fig 1: Ultrasound image of uterus

 

Fig 2: Plain CT image at the level of uterus
Fig 3: Contrast CT image at the level of uterus

 

Fig 1: Ultrasound image of uterus shows a hyperechoic lesion with a partially hypoechoic rim
Fig 2: Plain CT image at the level of uterus shows a well-marginated  predominantly fat-containing mass arising from uterus
 
Fig 3: Contrast CT image at the level of uterus shows minimal enhancement of the the lesion
Final Diagnosis Uterine lipoleiomyoma

 

Uterine lipoleiomyoma:

 

Uterine lipoleiomyomas result from degeneration of smooth muscle cells in an ordinary leiomyoma and represent a rare benign tumour of the uterus.

Epidemiology

Lipoleiomyomas have a reported incidence of 0.03-0.20% and are typically found in postmenopausal patients with typical uterine leiomyomas.

Clinical presentation

Although most patients are asymptomatic, they can present with symptoms similar to leiomyomas of the same size and location. Symptoms include, but are not limited to, abdominal/pelvic pain, palpable mass and menstrual abnormalities.

Pathology

Many considered a uterine lipoleiomyoma as a distinct variety of leiomyoma. Histologically, it is composed of variable amounts of adipocytes and smooth muscle cells, separated by thin fibrous tissue. The exact aetiology is not well known, but is thought to represent fatty metaplasia of the smooth muscle cells of a leiomyoma. Lesions can vary in size from a few mm to a few cm.

Radiographic features

Advanced imaging of these lesions allows for differentiation from cystic ovarian neoplasms, which may require surgical therapy.

Pelvic ultrasound

  • hyperechoic with a partially hypoechoic rim
    • the rim likely represents a layer of myometrium surrounding the fatty central component 
  • posterior acoustic attenuation
  • often poor vascularity on colour Doppler examination

CT

  • predominantly fat-containing mass arising from uterus
  • well-marginated 
  • often contains areas of soft tissue density

Pelvic MRI

Secondary to the predominant fatty component in the lesion, hyperintensity is seen on T1 weighted sequences and chemical shift artifacts are noted. Additionally, fat suppression techniques can be useful in verifying the diagnosis - most of the lesion shows fat suppression . Signal characteristics are therefore

  • T1: hyperintensity
  • T1 FS: hypointensity (saturates out)
  • T2: hyperintensity
  • T2 FS or STIR: hypointensity (saturates out)

Differential diagnosis

General imaging differential consderations include:

  • benign cystic ovarian teratoma
  • malignant degeneration of cystic teratoma
  • non-teratomatous lipomatous ovarian tumour 
  • pelvic lipoma 
  • pelvic liposarcoma
  • very rare lipomatous tumours of the uterus: angiomyolipoma, fibromyolipoma, myelolipoma