What are the other Names for this Condition? (Also known as/Synonyms)

• Localized Intraneural Type of Neurofibroma

What is Localized Intraneural Neurofibroma? (Definition/Background Information)

• A neurofibroma is a type of peripheral nerve sheath tumor (PNST). This tumor may arise from the nerves underneath the skin surface, or from nerves deep within the body
• Localized Intraneural Neurofibroma is the second-most common type of neurofibroma. It causes the localized enlargement of a nerve. Neurofibromas usually manifest in young men and women
• The risk factors for the development of neurofibroma is unknown in many cases. In some cases, multiple tumors may indicate the presence of neurofibromatosis type 1 (NF-1); solitary tumors are not associated with this genetic disorder
• Localized Intraneural Neurofibromas do not present any significant signs and symptoms in many cases. However, the tumors may involve the spinal nerves or cranial nerves; these tumors can cause associated signs and symptoms
• A treatment of the tumor may be undertaken, if they are of cosmetic concern to the individual. In such cases, a simple surgical excision is sufficient treatment. The prognosis is excellent on removal of Localized Intraneural Neurofibroma, since it is a benign tumor in many cases

Who gets Localized Intraneural Neurofibroma? (Age and Sex Distribution)

• Neurofibromas generally begin to appear during teenage and young adulthood (age range 15-20 years). But, they may be seen in individuals of any age group
• Both males and females are affected by Localized Intraneural Neurofibroma; no preference for any gender is seen
• This condition is observed worldwide; there is no ethnic or racial predisposition

What are the Risk Factors for Localized Intraneural Neurofibroma? (Predisposing Factors)

• No definitive risk factors for solitary Localized Intraneural Neurofibroma have been currently identified. A majority of the tumors are solitary and occur sporadically
• However, if more than one tumor is present, then an association with neurofibromatosis type 1 (NF-1) is observed. NF-1 is a genetic condition that is characterized by skin pigmentation and the formation of non-cancerous tumors that affect the central nervous system

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Localized Intraneural Neurofibroma? (Etiology)

The cause of Localized Intraneural Neurofibroma is due to genetic mutations.

• Currently, studies indicate defects in the following gene: NF1 gene
• Additionally, the following chromosomal aberration is noted:
  • Mutations in chromosome 17 due to loss of 17q (long arm); this is observed frequently
  • Mutations in chromosome 19 due to loss of 19p and 19q (on short arm and long arm respectively)
  • Mutations in chromosome 22 due to loss of 22q (long arm)
• In Localized Intraneural type of Neurofibroma, frequently, deletion in 9p is noted. It is also sometimes associated with abnormalities in the following genes:
  • CDKN2A
  • CDKN2B
  • MTAP

The above genetic abnormalities can be detected using molecular studies, which may play a significant role in identifying the tumor type, and in some cases, helping the healthcare provider take appropriate treatment decisions.

Note: The presence of multiple neurofibromas may indicate neurofibromatosis type 1, which is an autosomal dominant genetic disorder.

What are the Signs and Symptoms of Localized Intraneural Neurofibroma?

In many cases, significant signs and symptoms of Localized Intraneural Neurofibroma may not be observed. However, the following may be noted, in some cases:

• In most cases, the tumors are single and occur sporadically, not as part of a syndrome (non-syndromic tumors)
• In individuals with neurofibromatosis type 1, multiple tumors may be seen. In such cases, the associated signs and symptoms of NF-1 can be observed
• In many cases, the tumors are solid, firm, and mobile (when felt by touch)
• Intraneural neurofibromas can cause a localized, nodular enlargement of a nerve
• Some neurofibromas can be painful
• Deep neurofibromas involving major nerves can be quite large
• A common site of involvement is around the spinal cord, involving the spinal nerves and spinal nerve plexus
• This is followed by tumor involvement of the cranial nerves (nerves that originate from the brain)

If multiple tumors are noted, then it may occur against a background of neurofibromatosis type 1. In such cases, the associated signs and symptoms of NF-1 can be observed.

How is Localized Intraneural Neurofibroma Diagnosed?

A diagnosis of Localized Intraneural Neurofibroma may involve the following procedures and tests:

• Complete physical examination with evaluation of medical history
• Imaging studies, such as CT/MRI scans, of the affected region
• Tissue biopsy: A tissue biopsy is performed and sent to a laboratory for a pathological examination. The pathologist examines the biopsy under a microscope. After putting together clinical findings, special studies on tissues (if needed) and with microscope findings, the pathologist arrives at a definitive diagnosis

A differential diagnosis may be undertaken to eliminate the following tumor types prior to a definitive diagnosis:

• Neurotized nevus
• Schwannoma
• Spindle cell lipoma
• Superficial angiomyxoma
• Traumatic neuroma

Note: If there are multiple neurofibroma tumors, then it is an important diagnostic indicator for the presence of neurofibromatosis type 1 (NF1) disorder.

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Localized Intraneural Neurofibroma?

Generally, no significant complications arise from Localized Intraneural Neurofibroma; however, in some cases, the following may be observed:

• These tumors may present cosmetic concerns, in which case a surgery may be proposed
• Rarely, they can become malignant; the neurofibroma may undergo a malignant transformation
• Tumor recurrence following surgery
• Complications may arise due to NF1 (if present)

How is Localized Intraneural Neurofibroma Treated?

In majority of cases, Localized Intraneural Neurofibromas are asymptomatic and no treatment may be required; or, they may be treated for cosmetic issues. The treatment measures adopted may include:

• The healthcare provider may choose to regularly monitor the tumor, if they are asymptomatic
• A complete surgical excision and removal can result in a cure
• Treatment of underlying neurofibromatosis type 1 (if present) may be necessary
• Follow-up care with regular screening and check-ups are important

How can Localized Intraneural Neurofibroma be Prevented?

Current medical research has not established a definitive method to prevent the formation of sporadic Localized Intraneural Neurofibroma. However, if the tumors are present against a background of neurofibromatosis type 1, then the following may be considered:

• Genetic testing of the expecting parents (and related family members) and prenatal diagnosis (molecular testing of the fetus during pregnancy) may help in understanding the risks better during pregnancy
• If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
• Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders

What is the Prognosis of Localized Intraneural Neurofibroma? (Outcomes/Resolutions)

• In general, the prognosis of Localized Intraneural Neurofibroma is excellent on its complete excision and removal. Since many are benign tumors, the prognosis is excellent, even if only periodic observation is maintained
• In rare cases, solitary intraneural neurofibroma that involves large nerves can be premalignant. Such malignant transformations are increased in those with neurofibromatosis type 1 disorder
• The prognosis of Localized Intraneural Type of Neurofibroma associated with NF1, depends upon the severity of the signs and symptoms of the genetic disorder

Additional and Relevant Useful Information for Localized Intraneural Neurofibroma:

There is no definitive proof that certain types of diet may influence the development of neurofibromas.