Case Id: JSSMCRADC0057
They result from degeneration of smooth muscle cells in an ordinary leiomyoma and represent a rare benign tumour of the uterus.
Lipoleiomyomas have a reported incidence of 0.03-0.20% and are typically found in postmenopausal patients with typical uterine leiomyomas.
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.
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.
- 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
- predominantly fat-containing mass arising from uterus
- often contains areas of soft tissue density
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 Fat Sat: hypointensity (Fat is suppressed)
- T2: hyperintensity
- T2 Fat Sat or STIR: hypointensity
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