Neurofibroma is a common benign peripheral nerve sheath tumor; the other nerve sheath tumors being schwannomas and neurofibromatosis. Neurofibroma is made up of Schwann cells, fibroblasts, perineural cells, and trapped axons. They are unencapsulated nerve sheath lesions that mostly occur as a solitary localized nodule or as diffuse thickening of the skin and subcutaneous tissue. It can also be found as a plexiform variant that is a multinodular growth of major and minor nerves. It is often seen as a soft, grossly nodular or pedunculated, grayish-white mass with no secondary degenerative changes. They are mostly seen in young adults.(1)
How Dangerous Is Neurofibroma?
Neurofibroma is a relatively benign tumor with an extremely rare chance of local recurrence after complete excision of the tumor. The risk of malignant transformation is also extremely rare, which is only seen in the plexiform subtype of neurofibroma, which in itself is extremely rare. Malignant transformation is seen in 10% of patients with neurofibromatosis type 1. Type 1 neurofibromatosis is closely related to plexiform neurofibroma.(3)
The complication associated with localized neurofibroma is mild and related to surgical excision, which includes pain, bleeding, scarring, and local infection. In plexiform variant also the complication is associated with the risk of surgery and the inability to completely excise the tumor that may have esthetic implications.(3)
Is Neurofibroma Contagious?
In both the forms of neurofibroma, sporadic and neurofibromatosis type 1 syndrome, it is a result of a deletion in the NF1 gene and its mutation. Patients with neurofibroma are mostly asymptomatic, although irritation, mild itching, pain or paresthesia may occur. The clinical presentation depends on the type of neurofibroma; however, the most common complaint is related to esthetics. Solitary lesions are mostly less than 2 cm in diameter and have a characteristic ‘buttonhole sign’, which retracts on palpation and reappears on pressure release. Although localized lesions can appear anywhere in the body, they are most commonly found in the trunk, head, neck, and extremities. They are mostly confused with nevi or skin tags.(3)
Diffuse neurofibromas are mostly found on the head, neck, trunk, and extremities.They can surround various nerve fascicles and can have a larger diameter than solitary lesions. Paresthesia may be present if the lesion is large. Plexiform neurofibromas are also present on head, neck, trunk, and extremities. They can be superficial presenting as skin-colored or hyperpigmented nodules and deep that arise from spinal nerve roots and become highly irregular and tortuous. Deep lesions are often associated with pain, numbness, mass effect and sequelae of spinal nerve compression.(3)
Since neurofibromas are tumors of the peripheral nerve sheath and caused due to mutations, they are not contagious and cannot be spread from one person to another; however, they can be familial if associated with type 1 neurofibromatosis.
Neurofibroma can be divided into localized, diffuse and plexiform subtypes. The localized subtype is the most common type of neurofibroma accounting for nearly 90% of all the cases of neurofibroma. Localized neurofibroma accounts for approximately 5% of all benign soft tissue tumors; it is seen in young individuals around 20-30 years of age. Most of the tumors are superficial tumors that originate from small nerves; however, deep-seated tumors originating from major nerves have also been encountered.
Clinically patients present with a painless, soft tissue mass that is slow-growing.(2)
Plexiform neurofibroma tumor is more common during childhood and is associated with type 1 neurofibromatosis. It is also associated with malignant transformation and the lifetime risk is around 8-12%. As compared to its localized counterpart, plexiform neurofibroma expands and distorts a large portion of the nerve and its branches that create a ‘bag of worms’ appearance on macroscopic examination. When an entire limb is affected by plexiform neurofibroma, a condition known as elephantiasis neuromatosa might be induced that is associated with enlargement of the affected extremity, bone hypertrophy, and skin enlargement. It also invades adjacent muscles and connective tissue.(2)