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Soft Tissue Tumors
Angiolipoma
Author: Nat Pernick, M.D., PathologyOutlines.com, Inc.
Reviewer: David Lucas, M.D., University of Michigan Health Systems (January 2009)
Revised: 26 June 2009, last major update June 2009
Definition
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● Subcutaneous nodule composed of mature adipocytes, thin walled vessels and fibrin thrombi
● See also Breast chapter
Terminology
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● Infiltrating (intramuscular) angiolipoma is no longer acceptable terminology because it represents a different lesion; 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be an intramuscular large vessel hemangioma in which muscle has been replaced by fat (J Pediatr Orthop 1986;6:172)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
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● Usually skin, 2/3 in forearm and chest wall
● Painful, usually multiple subcutaneous nodules (other painful nodules are angioleiomyoma, eccrine spiradenoma, glomus tumor and traumatic neuroma)
● May actually be hemangiomas containing fat, not mixed tumors
Case reports
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● 25 year old man with multiple tumors, with minimal adipose (Am J Dermatopathol 1995;17:312)
● 71 year old woman with epidural tumor (J Clin Pathol 2005;58:882)
● 47 year old man with foot tumor (World J Surg Oncol 2008;6:11)
Treatment and prognosis
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● Excision; does not recur or metastasize
Clinical images
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Mass on plantar surface of foot
Gross description
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● Encapsulated, small (< 2 cm), yellow-red nodule in subcutaneous tissue
Gross images
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Foot mass with Small bowel tumor
vascular pedicle
Mediastinal tumor Epidural tumor is hemorrhagic and spongy
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 (AJSP 1990;14:75)
● Mast cells are present
● Fibrosis in older lesions
Micro images
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Mature adipose tissue and Prominent vascular thrombi
prominent vasculature
Prominent vascular thrombi Prominent vascular thrombi
Prominent vascular thrombi Prominent vascular thrombi
Other images: mature adipose tissue and prominent vasculature; prominent vascular thrombi
Electron microscopy
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● May have reduced number of Weibel-Palade bodies in endothelial cells (Hum Path 1981;12:739)
Molecular / cytogenetics
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● Almost always normal karyotype
Differential Diagnoses
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● Kaposi’s sarcoma and angiosarcoma - not circumscribed, usually not subcutaneous, atypia present, no scattered adipocytes
Additional references
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End of Soft Tissue Tumors > Angiolipoma
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