Fibrolipomatous Hamartoma
Cyril Fisher, MD, DSc, FRCPath
Key Facts
Terminology
Increased fibrofatty tissue infiltrating and surrounding nerves
Clinical Issues
Median nerve most commonly affected
Predominantly in children, including congenitally
Macrodactyly
Complete excision contraindicated because of nerve damage
Macroscopic Features
Sausage-shaped mass
Can extend into adjacent soft tissue of hand and wrist
Microscopic Pathology
Adipose tissue and fibrous tissue
Perineurium can become hyperplastic
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
Fibrolipomatous hamartoma of nerve
Lipofibromatous hamartoma of nerve
Neural fibrolipoma
Neurolipomatosis, lipomatosis of nerve
Definitions
Increased fibrofatty tissue infiltrating and surrounding nerves
CLINICAL ISSUES
Epidemiology
Age
Predominantly in children, including congenital lesions
Some cases in young adults up to 30 years of age
Rarely in older adults
Site
Affects palmar surface of hand, wrist, forearm
Median nerve and branches most commonly affected
Rarely involves ulnar or radial nerve
Involves left arm more often than right arm
Very rarely involves sciatic, peroneal, or cranial nerve
