Clinical Discussion:
Angiolipomas are tumors of fat tissue, and may occur sporadically, as a result of trauma, or may be associated with genetic conditions. Angiolipomas are similar to ordinary lipomas, except with proliferating capillary lobules that are often thrombosed, causing pain (in contrast to asymptomatic lipomas). Angiolipomas generally affect younger adults and commonly occur as multiple lesions on the upper extremities and trunk. These are benign lesions and do not have malignant potential.
Lymphadenopathy would not be expected to be generalized and tender, ongoing for two years in an otherwise healthy person. Osteosarcoma would present with a fixed, hard lesion, and would be expected to be associated with other signs such as fevers and weight loss, especially with multiple lesions, as in this case. Keratoacanthoma presents as an erythematous epidermal dome-shaped nodule with central keratin-filled crater. Epidermal inclusion cysts are more firm, well-circumscribed and are follicular cysts with an overlying punctum, often with a history of draining a malodorous discharge.
Microscopic Discussion:
Angiolipoma is a relatively common, benign tumor of fat. As with common lipomas, they are well-circumscribed and composed of normal-appearing adipocytes. Angiolipomas are further characterized by areas composed of capillary-sized blood vessels that may make up anywhere between 5 to 95% of the lesion. Fibrin thrombi within capillaries is a common findings, and accounts for clinical tenderness that patients frequently report with these lesions.