Myolipoma of soft tissue
Myolipoma of soft tissue is a benign soft tissue tumor mainly consisting of well-differentiated smooth muscle cells and mature adipose tissue.
Terminology
Myolipoma of soft tissue is also known under the name ‘extrauterine lipoleiomyoma’.
Epidemiology
Myolipomas are rare, they are more common in women and seen in the 5 and 6 decades of life .
Clinical presentation
Patients might present with a palpable lump if the myolipoma is located at the trunk or extremities. Tumors in the abdominal cavity and retroperitoneum are mostly asymptomatic and found incidentally .
Pathology
Myolipomas consists of mature fat cells and well-differentiated spindled, smooth muscle cells. They can grow quite large if previously undetected .
Location
- abdominal cavity
- retroperitoneum
- pelvic cavity e.g. at a presacral location
- inguinal region
- subcutaneous tissues of the trunk and/or extremities (rarely)
Macroscopic appearance
Myolipomas are usually circumscribed and surrounded by a capsule and consists of adipose tissue and smooth muscle cells .
Microscopic appearance
Smooth muscle component is often interspersed with mature adipose tissue, predominates over the latter and is positive with immunohistological stains for smooth muscle actin and desmin .
Radiographic features
CT
Relatively circumscribed, fat-containing heterogeneous mass with hypodense fat tissue components and soft tissue density muscular components .
MRI
Usually shows a fat-containing heterogenous mass with interposed soft tissue density reflecting the smooth muscle components.
- T1: heterogeneous intermediate signal intensity
- T2: heterogenous intermediate to high signal intensity
- T2FS: heterogenous
- T1C: heterogeneous enhancement
Treatment and prognosis
Treatment options includes resection, which is curative.
Differential Diagnosis
- well-differentiated liposarcoma
- spindle-cell lipoma
- angiomyolipoma
- leiomyoma with fatty degeneration
See also
