Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Sara Mohsin, M.D.[2]
Overview
Neurofibroma may be classified into 5 subtypes: cutaneous/dermal/localized, subcutaneous, diffuse, intramuscular, and plexiform neurofibroma. Plexiform neurofibromas may be further sub-classified into diffuse and nodular plexiform.
Classification
Neurofibroma may be classified into following 5 subtypes:[1][2]
| Types of neurofibromas
|
Characteristics/Description
|
| Cutaneous/Dermal/Localized (90%)
|
- Most common
- Occurs as lumps or bumps on skin
- Painless
- Slowly growing
- < 5cm diameter
- Starts in teenage years or young adults and rarely starts in childhood
- Increase in size and number over the years
- Clearly defined borders hence, can be removed if necessary
- Number of skin tumors in each patient varies tremendously
- Mostly solitary and sporadic, not associated with NF1
|
| Subcutaneous
|
|
| Diffuse
(superficial)
|
- Superficial
- Uncommon
- Feels soft and squishy
- Usually involves scalp or trunk (often protruding out, like a “love handle”)
- Ill defined margins, can't tell where tumor stops
- Runs through the full skin thickness (from the surface all the way down to the base of the skin (subcutaneous fascia/fat)
- Doesn't go deeper than fascia
- Usually seen in early childhood and young adults
- Usually associated with diffuse hyperpigmentation, so looks like a very large squishy café au lait spot
- Solitary lesions and not related to any inherited condition
|
| Intramuscular
|
- Common
- Usually isolated tumors in the muscle
- Growths along very small nerves
- Causes pain sometimes
- Can be removed (leaves a scar behind)
- Sometimes can occur as plexiform neurofibromas in form of chains or networks
|
| Plexiform/Intraneural
(deep)
|
- Deep
- Associated with NF1
- Diffuse involvement along a large nerve and its branches
- Mostly internal/ intraneural
- Can also involve small nerves and superficial skin
- Have more connective tissue/extracellular matrix than cutaneous neurofibromas, that separates the nerve fibers
- Gross enlargement of the nerve with nodular tumor development results in the gross pathologic appearance referred to as “bag of worms”
- Generally believed to be present at birth (congenital)
- Disfiguring
- Affects function due to sheer size as well as neurovascular compromise
- Plexiform neurofibroma exhibits following features on T2-weighted MRI:
- Target sign (low signal intensity centrally with a ring of high signal intensity peripherally)
- Fascicular sign
- May appear as a larger and more infiltrating mass with lobulated borders with inhomogeneous enhancement
|
Plexiform neurofibromas can be further subclassified into following:[3]
References
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