Angiolipoma
Angiolipoma is a benign subcutaneous tumor composed of fat and vessels. Approximately 5% of cases are familial (e.g., benign familial angiolipomatosis). Angiolipomas are usually found in young adults. There may be no symptoms, or the lesion may be tender. Clinically, the lesion is a soft skin-colored plaque or nodule resembling lipoma. The most common site is the forearms followed by the trunk and upper arms. Multiple angiolipomas are frequently found. As no genetic abnormality has been found many believe angiolipoma is best considered a hamartoma rather than a true neoplasm. Although angiolipomas usually do not exceed 5 cm in size, they can reach massive size according to a few reports in the literature 1.
A family history is found in about 10% of angiolipoma cases, but no pattern of inheritance has been proposed. A history of previous trauma to the site or the therapeutic use of protease inhibitors is rarely elicited. Numerous angiolipomas appeared in a young adult male with familial angiolipomatosis upon starting anabolic steroids 2. Mild pain or discomfort is often noted when pressure is applied or the lesions are moved; the pain appears to be related to the vascularity of the lesions.
Angiolipomas can present in many different locations some reports include thyroid, intraosseous, breast, gastrointestinal tract and can mimic otherwise concerning conditions there but there is no evidence that cutaneous angiolipomas are related to their presence.
Surgery is curative, but not essential as angiolipomas are benign. Angiolipomas tend to be well-circumscribed and easily removed.
Angiolipoma causes
The cause of angiolipoma is unknown, but it involves fat accumulation, with increased microvasculature and characteristic microthrombi. In about 5% of cases, multiple angiolipomas can be inherited in autosomal dominant fashion (e.g., benign familial angiolipomatosis), which suggests a genetic anomaly that has not been identified. In contrast to lipomas, which are composed only of mature lipocytes, angiolipomas are comprised of mature lipocytes and numerous, thin-walled blood vessels that are often thrombosed.
Angiolipoma symptoms
Angiolipoma clinical features:
- Angiolipomas usually develop in adulthood (20–40 years), but they can also present in younger or older patients. Angiolipomas are rare in children.
- Angiolipomas may appear anywhere on the body. Most occur on the upper trunk and upper extremities. The forearm is the site most often affected.
- Angiolipomas are often asymptomatic but can be tender or painful, especially when compressed.
- More than 90% of cutaneous angiolipomas are 2 cm or larger.
- Angiolipomas present as skin-colored or slightly violaceous, soft to slightly firm, well-circumscribed, subcutaneous lesions. When multiple lesions are present, there is often general symmetry.
- Most cases are slightly mobile with palpation.
- Rare cases can compress adjacent nerves, yielding a peripheral neuropathy.
- Rare cases can develop a locally aggressive growth pattern, with infiltration into skeletal muscle.
Angiolipoma complications
Complications of angiolipoma may include ulceration, sepsis, gangrene and possible systemic inflammatory response syndrome which may pose a threat to the patient’s life, hence should be managed promptly after adequate patient preparation 3.
Angiolipoma diagnosis
Angiolipomas may be difficult to distinguish from other fatty tumours such as lipoma on clinical examination. Angiolipomas are often diagnosed based upon the history and clinical presentation of a long-standing, slow-growing, soft, and well-circumscribed subcutaneous nodule, with a fatty consistency. Angiolipomas are more likely to be painful, in comparison to common lipomas.
If the diagnosis is in question, a biopsy may be performed. It must be remembered that the findings of interest exist deep in the soft tissue, and an incisional or excisional biopsy may be necessary. Angiolipoma can be distinguished histologically, following biopsy, by the finding of vessels (particularly if thrombosed) within a proliferation of mature fat cells.
Rare cases potentially associated with a peripheral neuropathy may require MRI for assessment.
Angiolipoma histology
Angiolipomas are small (less than 2 cm) encapsulated tumors composed of mature fat in association with a proliferation of benign, thin-walled blood vessels, some of which have intravascular fibrin thrombi. The proportion of the different components can be quite variable in individual tumors.
Sections through angiolipoma show nonseptate fat with peripheral congeries of small capillaries. Some of the capillaries are plugged with fibrin thrombi.
Sometimes, there are only rare adipocytes admixed with numeous capillaries (“cellular angiolipoma”).
Differential diagnosis of angiolipoma pathology
Cellular lesions and angiolipomas with massive intravascular thrombosis may be confused with rarer vascular lesions (such as kaposiform haemangioendothelioma).
Angiolipoma treatment
Angiolipomas are benign. No treatment is required. Lesions that are painful, or for which removal is otherwise desired, can be treated with surgical extirpation, in a manner similar to that for lipomas. Liposuction surgery can be performed in select cases.
Angiolipoma prognosis
Untreated, angiolipomas usually reach a stable size and persist indefinitely. Malignant transformation to liposarcoma has not been observed in angiolipomas.
References- Papakonstantinou P, Korkolopoulou P, Lassithiotakis D, Lolis E. Giant angiolipoma of the arm in an elderly patient. Ann R Coll Surg Engl 2016; (6): e100–e102.
- Weedon’s Skin Pathology 3rd Edition, 2010. ISBN: 978-0-7020-3485-5
- Elfallal AH, Laimon YN, Emile SH. Giant angiolipoma of the back complicated with ulceration and sepsis: unusual presentation of a rare benign tumour. Ann R Coll Surg Engl. 2019;101(3):e91–e93. doi:10.1308/rcsann.2018.0221 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6400908
