Age / Sex : 17 / M

C.C. mass-like lesion at right thigh


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Courtesy : 이인숙 (In Sook Lee), 부산대병원 (Pusan National University Hospital)

angiolipoma

Discussion

Findings
1. hyperechoic fatty mass lesion with vascularity at US
2. most fat component at background with prominently septal or superficial fascial thickening and prominent vascularity at subcutaneous fat

Discussion
- Introduction
Benign soft tissue tumors of mesenchymal origin which are made of mature adipocytes with an excessive degree of vascular proliferation
Occur in every part of the body, but they are more common on the extremities (2/3 of the cases in the forearm), trunk, spinal axis, head, and neck.
Size; almost never exceeds 4 cm
often asymptomatic and painless except when they cause a mass effect.
The pathogenesis ; still unclear, but acute or recurrent trauma has been suggested as a possible etiologic factor

- Type
Two types; infiltrative & noninfiltrative types.
1. Encapsulated/noninfiltrative type
resented as subcutaneous nodule
commonly multiple, typically firm, tender to palpation but often painful
rarely associated with overlying skin changes
2. The rare infiltrative, nonencapsulated type
typically involves deep soft tissues
separated from the cutaneous (encapsulated) lesion because of its growth pattern and tendency to recur locally (now best classified as intramuscular hemangioma).

- Imaging modalities
Ultrasonography
: not very specific but can be useful for differentiating subcutaneous angiolipomas from ordinary lipomas by observing color Doppler flows
CT contrast scans
: a central low-density mass (lipomatous component) surrounded by areas of contrast enhancement (vascular component)
CT without contrast
: the homogenous low attenuation of a typical lipoma and may not define the margins and the exact extent of the lesion.
MRI with contrast
: defines well the margins of the lesion and demonstrates the presence of septa and the enhancement reveals the dense capillary proliferation.

- Treatments
1. noninfiltrating angiolipomas; simple surgical excision, no tendency to recur.
2. infiltrating angiolipomas; wide surgical excision, recurrence rate of 50%.
3. no pain or a small size (under 5 cm); followed up without surgical treatment 

Referenes
1. skeletal Radiol 2023;52(3):541-552. Angiolipoma: a review of 778 lesions in 344 patients
2. Case Rep Orthop 2021;2021:4047777. Giant posttraumatic angiolipoma of the forearm: a case report and review of the literature.
3. Korean J Radiol 2013;14(5): 810-817. MRI features of spinal epidural angiolipomas