Fibrolipomatous Hamartoma
Cyril Fisher, MD, DSc, FRCPath
Key Facts
Terminology
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Increased fibrofatty tissue infiltrating and surrounding nerves
Clinical Issues
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Median nerve most commonly affected
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Predominantly in children, including congenitally
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Macrodactyly
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Complete excision contraindicated because of nerve damage
Macroscopic Features
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Sausage-shaped mass
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Can extend into adjacent soft tissue of hand and wrist
Microscopic Pathology
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Adipose tissue and fibrous tissue
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Perineurium can become hyperplastic
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Nerve bundles become separated
MR of the wrist shows abnormal fat signal  in the stroma between the nerve fascicles (black dots) of an enlarged median nerve. |
Hematoxylin & eosin shows accumulation of mature adipose tissue with hypocellular fibrous septa around and between nerve bundles. |
TERMINOLOGY
Synonyms
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Fibrolipomatous hamartoma of nerve
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Lipofibromatous hamartoma of nerve
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Neural fibrolipoma
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Neurolipomatosis, lipomatosis of nerve
Definitions
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Increased fibrofatty tissue infiltrating and surrounding nerves
CLINICAL ISSUES
Epidemiology
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Age
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Predominantly in children, including congenital lesions
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Some cases in young adults up to 30 years of age
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Rarely in older adults
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Site
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Affects palmar surface of hand, wrist, forearm
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Median nerve and branches most commonly affected
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Rarely involves ulnar or radial nerve
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Involves left arm more often than right arm
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Very rarely involves sciatic, peroneal, or cranial nerve
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