What is Angiolipoma?
Angiolipoma is a benign soft tissue tumor composed of mature adipose tissue (fat cells) and proliferating blood vessels, most commonly occurring as small, subcutaneous, tender-to-painful nodules in young adults, with a predilection for the trunk and forearms. 1, 2
Histological Composition
Angiolipomas are histologically characterized by:
- Mature fat cells (adipocytes) mixed with proliferating vascular elements 1
- Small blood vessels that are evenly distributed throughout the tumor 1
- Fibrin thrombi frequently present within vascular lumina 3
- Well-demarcated but typically nonencapsulated lesions 3
Clinical Characteristics
Typical Presentation
- Most commonly affects young males as multiple small subcutaneous nodules 3
- Characteristically tender or painful, distinguishing them from ordinary lipomas 2, 3
- Predilection sites include forearms, trunk, and extremities 1, 2, 4
Size Classification
- Angiolipomas larger than 4 cm are classified as "giant" and require histological evaluation to exclude malignancy 4
Anatomical Variants and Rare Locations
While subcutaneous tissue is the typical location, angiolipomas can occur in unusual sites:
- Spinal canal (60 reported cases), showing female predominance (1.6:1) with mean age 43 years, typically presenting with cord compression 2
- Head and neck region, including buccal mucosa 1
- Intramuscular locations, including posttraumatic cases 4
- Gastric wall (only 4 reported cases) 5
- Intranodal (within lymph nodes), which must be distinguished from metastatic disease 3
Important Clinical Distinctions
Differentiation from Angiomyolipoma
Angiolipoma should not be confused with angiomyolipoma (AML), which is a completely different entity:
- Angiomyolipomas are renal tumors composed of blood vessels, smooth muscle, and fat, commonly associated with tuberous sclerosis complex (TSC) 6, 7
- Renal angiomyolipomas carry bleeding risk when >4 cm and require specific management protocols 6
- Adrenal angiomyolipomas require functional evaluation and size-based management algorithms 8
Diagnostic Considerations
- Histological evaluation is necessary for giant angiolipomas (>4 cm) to exclude malignancy 4
- When occurring in lymph nodes, must be distinguished from metastatic lesions or malignant vascular tumors 3
- Gastric angiolipomas require differentiation from other benign and malignant gastric neoplasms 5
Management
Surgical excision is the definitive treatment for symptomatic angiolipomas 1, 2, 4
- Complete surgical removal or decompression is most satisfactory for spinal cases 2
- Postoperative prognosis is excellent for completely resected benign lesions 4
Common Pitfalls
- Do not confuse angiolipoma with angiomyolipoma—these are distinct entities with different clinical implications and management strategies 6, 1
- Intranodal angiolipomas can mimic metastatic disease; histological confirmation is essential 3
- Posttraumatic presentation is possible, including after venipuncture 4