Angiolipoma

 Male predominance



• Forearm, trunk, and upper arm most common sites

• Painful tender subcutaneous nodules
image Often multiple

• Treatment: Simple surgical excision

• Excellent prognosis
image Local recurrence very rare

image No risk of malignant transformation




Macroscopic




• Circumscribed, yellow-red nodule

• Typically < 2 cm in size


Microscopic




• Admixture of mature adipocytes and capillary-sized blood vessels
image Hallmark: Fibrin thrombi within vessels

• Vascularity often more prominent in periphery

• No nuclear atypia in adipocytic or endothelial components

• Morphologic variant: Cellular angiolipoma


Top Differential Diagnoses




• Lipoma

• Intramuscular hemangioma

• Kaposi sarcoma

• Spindle cell hemangioma

• Angiomyolipoma

image
Angiolipoma at Low Magnification
Angiolipoma is composed of both vascular image and mature adipocytic image components admixed together in varying proportions. They are often small, circumscribed lesions, as seen here.


image
Prominent Adipose Tissue Component
This angiolipoma is predominantly composed of adipose tissue. The focal vascular component is present as clusters of small vessels near the periphery image and around the thin, fibrous septa image.

image
Peripheral Vascular Component
The focal vascular component of angiolipoma is present as clusters of small vessels near the periphery of the lesion image. The remainder of the tumor is composed of mature adipocytes image.

image
Characteristic Fibrin Thrombi
Bright pink fibrin thrombi image are present in small clustered capillary vessels. This is the hallmark feature of angiolipoma.


TERMINOLOGY


Definitions




• Benign tumor composed of mature adipocytes and clustered small blood vessels with intraluminal fibrin thrombi


ETIOLOGY/PATHOGENESIS


Unknown




• Majority are sporadic

• Rare familial predilection (5%)


CLINICAL ISSUES


Epidemiology




• Age
image Most common in young adults

image Rare in children or in adults > 50 years

• Sex
image Male predominance


Site




• Forearm, trunk, and upper arm most common sites

• Rare on scalp or face

• May occur in subcutis of breast (causing clinical concern for neoplasm of breast parenchyma)


Presentation




• Painful subcutaneous nodule, often multiple (in 2/3 of cases)
image No correlation between pain and degree of tumor vascularity


Treatment




• Simple surgical excision


Prognosis




• Excellent: Benign
image Very low risk of local recurrence

image No known risk of malignant transformation


MACROSCOPIC


Gross Features




• Well circumscribed

• Yellow-red nodules

• Typically < 2 cm in size


MICROSCOPIC


Histologic Features




• 2 components present in varying proportions
image Mature adipocytes

image Clustered capillary-sized vessels with fibrinoid thrombi

– Vascularity often more prominent in periphery

• No nuclear atypia in adipocytic or endothelial components

• Fibrosis may be present around vessels and between adipocytes in late stage of lesion

• Mast cells may be conspicuous in some cases

Apr 24, 2017 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Angiolipoma
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