Soft Tissue Tumors - Angiolipoma

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Soft Tissue Tumors

Adipose tissue

Angiolipoma

Reviewer: Vijay Shankar, M.D. (see Reviewers page)
Revised: 4 November 2012, last major update August 2012
Copyright: (c) 2003-2012, PathologyOutlines.com, Inc.

See also Breast chapter

General
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● Subcutaneous nodule composed of mature adipocytes, thin walled vessels and fibrin thrombi

Terminology
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● Infiltrating (intramuscular) angiolipoma is no longer acceptable terminology because it represents a different lesion (Stanford University)
● May be an intramuscular large vessel hemangioma in which muscle has been replaced by fat (J Pediatr Orthop 1986;6:172)

Epidemiology
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● Arises shortly before puberty or in young adults
● Rare in children or older adults
● 5% familial

Clinical features
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● Usually skin, 2/3 in forearm and chest wall, can occur on thighs, distal extremity
● Rarely in the head and neck region
● Painful, usually multiple subcutaneous nodules (other painful nodules are angioleiomyoma, eccrine spiradenoma, glomus tumor and traumatic neuroma)
● May actually be hemangioma containing fat, not a mixed tumors

Case reports
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● 9 year old girl with swelling in the upper lip (J Oral Maxillofac Pathol 2012;16:103)
● 25 year old man with multiple tumors but with minimal adipose (Am J Dermatopathol 1995;17:312)
● 47 year old man with foot tumor (World J Surg Oncol 2008;6:11)
● 69 year old man with spinal tumor (Neurol Med Chir (Tokyo) 2011;51:539)
● 71 year old woman with epidural tumor (J Clin Pathol 2005;58:882)

Treatment and prognosis
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● Excision
● Does not recur or metastasize

Clinical images
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Various images

Gross description
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● Encapsulated, small (< 2 cm), yellow-red nodule in subcutaneous tissue

Gross images
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Various images

Other images: lobulated fat with thin fibrous septae and brown spots representing thrombosed capillary vessels

Micro description
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● Mature adipose tissue, branching capillaries and thick walled vessels with pericytes, particularly at periphery
● Hyaline/fibrin thrombi are an important diagnostic sign
● Cellular tumors are usually encapsulated with septation and fibrin thrombi (Am J Surg Pathol 1990;14:75)
● Mast cells are present
● Fibrosis in older lesions

Micro images
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Mature adipose tissue and prominent vasculature

Prominent vascular thrombi

Various images

9 year old girl wit lesion on lip

● Other images: mature adipose tissue and prominent vasculature, prominent vascular thrombi

Virtual slides
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Virtual slide

Electron microscopy description
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● May have reduced number of Weibel-Palade bodies in endothelial cells (Hum Pathol 1981;12:739)

Molecular/cytogenetics description
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● Almost always normal karyotype

Differential diagnosis
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● Kaposi’s sarcoma and angiosarcoma: - not circumscribed, usually not subcutaneous, atypia present, no scattered adipocytes

End of Soft Tissue Tumors > Adipose tissue > Angiolipoma

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