Neurofibromatosis is usually manifested by pigmentation patterns on the skin. In neonates, these appear as evenly pigmented, variously shaped café-au-lait brown macules, which increase in number during the first few years of life [23]. In late adolescence, neurofibromas are found in the skin. Chief complains are cutaneous discoloration or disfigurement, pain, pathologic fractures, and hypertensive headaches due to pheochromocytoma (tumor of the sympathetic paraganglia).

NF1 tumors consist of mast cells, fibroblasts, Schwann cells, and vascular components which develop at any point along a nerve. Three known subtypes of neurofibroma are: cutaneous, subcutaneous, and plexiform. Cutaneous lesions and subcutaneous lesions are in the form of circumscribed nodules, brown or pink or the color of skin, soft or firm to touch, and invaginates when pressed with a finger (a pathognomonic sign). None of these are specific for type 1 neurofibromatosis. 

Plexiform neurofibromas are noncircumscribed, pleomorphic and thick lesions. These are pathognomonic of NF1 [24] and can cause disfigurement by integrating with important supportive structures. Other neural disorders such as malignant peripheral nerve sheath tumors, schwannomas, and granular cell tumors have been associated with NF1 [25].

Although plexiform neurofibromas infiltrate the orbit, temporal region, or eyelids less frequently than optic nerve gliomas, these serve as a potential cause of loss of vision. Strabismus (squinting), proptosis (exophthalmos) and changed globe length are caused by orbitotemporal neurofibromas. Amblyopia (double vision) in young children may result in obstruction of vision secondary to neurofibroma. A study of 21 children with plexiform neurofibroma of the orbitotemporal areas showed 6 cases of lid involvement and 3 with bilateral neurofibromas. Amblyopia was present in 62%, primarily from anisometropia and ptosis (drooping upper eyelid) [26].

Signs and symptoms of neurofibromatosis

Type 1 

Most patients are asymptomatic, if at all, some are with neurologic symptoms or bone deformities. Skin lesions appear in more than 90% of neonates: freckle-like, medium-brown (café-au-lait), macules on the trunk, pelvis, elbows and knees. Present during late childhood are numerous flesh-colored cutaneous tumors, rarely, plexiform neurofibromas appear as an irregularly thickened, grossly deformed structure. Unaffected children may have 2 or 3 café-au-lait macules whereas children with NF1 have as many or more than 6 macules.

Neurologic symptoms and bone abnormalities include:

• Scoliosis
• Pseudoarthrosis 
• Fibrous dysplasia
• Vertical scalloping
• Subperiosteal bone cyst
• Thinning of the long-bone cortex
• Posterior orbital wall is absent, with pulsating exophthalmos

Other clinical findings include: optic glioma and Lisch nodules (iris hamartomas) and changes in arterial walls leading to Moyamoya disease or intracranial artery aneurysms. Children have slightly larger heads and have learning problems. Chronic myelomonocytic leukemia and rhabdomyosarcoma may occur in children and adolescents. Pheochromocytomas affect all ages. Malignant tumors inlcude  supratentorial or brain stem gliomas. Plexiform neurofibromas may transform at any age to malignant peripheral nerve sheath tumors. 

Type 2

Bilateral acoustic neuromas occur in children and young adults, causing hearing loss, instability, headache or facial weakness. Bilateral 8th cranial (vestibulocochlear) nerve masses may be present. Other family members may develop gliomas, meningiomas, or schwannomas.

• Renal Artery Stenosis

  Blood pressure should be checked yearly because of the higher risk for hypertension due to renal artery stenosis, aortic stenosis, and pheochromocytoma (more common in adults). [hawaii.edu]

  While the cause for this is not certain, some cases may not directly relate to NF1, but rather to associated changes in the blood vessels leading to the kidneys (renal artery stenosis). [rarediseases.org]

  Discussion Clinical manifestations of NF1 include neurofibromas, café-au-lait spots, Lisch nodules, malignancy, skeletal manifestations, and cognitive deficits. 12,15,17,20,21,23,24 Vascular manifestations associated with NF1 include renal artery stenosis [stroke.ahajournals.org]

• Fatigue

  Our integrative health services feature massage therapy, which can help to reduce stress, and acupuncture, which may relieve fatigue. Our yoga program can help to encourage relaxation, improve strength, and create peace of mind. [nyulangone.org]

• Respiratory Distress

  Of the 70 cases, three cases had reticular opacities and other potential causes of their diffuse lung disease: residual scarring from acute respiratory distress syndrome; rheumatoid arthritis-related ILD and smoking-related ILD ( e.g. desquamative interstitial [erj.ersjournals.com]

• Long Arm

  The NF-1 gene is on the long arm of chromosome 17 and is a tumor suppressor gene. [hawaii.edu]

  Disease Neurofibromatosis type 1 (NF1) is an autosomal genetic disease caused by heterozygous dysfunction of the NF1 tumor suppressor gene on the long arm of chromosome 17. Embryonic origin Neurocrest. [atlasgeneticsoncology.org]

• Tinnitus

  Herein, we present the case of a previously healthy 54year-old female who developed several weeks of unilateral tinnitus and aural fullness. [ncbi.nlm.nih.gov]

  Ringing noises inside the ear (tinnitus), hearing loss and/or deafness. Cataracts at a young age. Spinal tumors. Balance problems. Wasting of muscles (atrophy). [genome.gov]

  Other complications related to the ear may include dizziness, ringing in the ears ( tinnitus ), and balance problems. The pressure from the tumours on other nerves may also cause headaches or numbness of the face or weakened facial muscles. [medbroadcast.com]

  An audiologist can advise on managing balance and tinnitus, or ringing in the ears. Some people with neurofibromatosis learn to lip read and use sign language. [medicalnewstoday.com]

  Nerve damage for individuals with NF2 may result in some, but not all, of the following: Ringing in the ears (tinnitus) Hearing loss Problems with balance Facial weakness Brain and cranial nerve damage Swallowing difficulties Seizures Vision loss Loss [ctf.org]

• Hearing Impairment

  All hearing-impaired people have the opportunity to communicate with their medical care team at NYU Langone with the assistance of signing facilitators or computer-assisted communication devices. [nyulangone.org]

  The management of NF-2 includes genetic counseling, annual hearing screenings, and surgery or radiation therapy for tumors. For those with severe hearing impairment, cochlear or brainstem implants may be considered (4). [hawaii.edu]

• Cafe-Au-Lait Spots

  Diagnosis The diagnosis of NF1 is usually made during the first decade of life, based on characteristic skin freckling, cafe-au-lait spots, optic glioma, and/or pseudoarthrosis. [rarediseases.org]

  Carriers of this autosomal dominant trait are prone to the occurrence of benign and malignant tumors which present with cafe-au-lait spots, fibromatous tumors in the skin and Lisch nodules in the eye. [symptoma.com]

  Six or more light brown-colored birthmarks (cafe-au-lait spots) may be located anywhere on the body. The spots usually appear before about 9 years of age. [orthoinfo.aaos.org]

• Vertigo

  Symptoms may include: facial numbness, weakness and sometimes paralysis gradual, or more rarely sudden, hearing loss loss of balance, dizziness, and vertigo tinnitus, or ringing in the affected ear Symptoms may get worse as the tumor grows. [medicalnewstoday.com]

On CT scan, tumors appear as a circumscribed hypodense mass with minimal contrast enhancement. With MRI lesions are T1 hypointense and T2 hyperintense with varied contrast enhancement. Localised neurofibroma is similar to schwannoma, with distinct, fusiform and encapsulated soft tissue masses less than 5 cm in diameter. Most NF1 patients are identified during routine consultation or for verification of a positive family history. MRI is recommended to establish the diagnosis of NF1 in patients with symptoms and signs of neurologic disorder and particularly in children with glioma, when visual testing is difficult. Acoustic neuromas or meningiomas of NF2 origin can be diagnosed with MRI in conjunction with CT of the petrous ridge, showing typical widening of the auditory canal.

• Mediastinal Mass

  These tumors may also appear as anterior mediastinal masses, sciatic nerve lesions with pelvic extension, and perirectal plexiform and uterine tumors, all leading to sever clinical complications. [atlasgeneticsoncology.org]

Treatment for neurofibroma, if at all, is selective, depending on the type of lesions i.e., localized, diffuse, and plexiform. In patients with severe symptoms, surgical removal or irradiation of the lesions may be required, provided that the possible damage to the involved nerve is taken into consideration.

Lesions not associated with NF1

Surgery is indicated for localized and diffuse lesions. However, since neurofibromas insinuate between nerve fascicles, it is difficult to perform complete excision without damaging the nerve. Deep-seated lesions are managed with the least intrusion on the parent nerve. No recurrence has been reported and malignant transformation is not the usual case [1].

Lesions associated with NF1

Patients with NF1 are treated conservatively (non-surgical) due to the presence of multiple lesions, unless the severity of symptoms require a more radical approach to treatment. Surgical excision of plexiform neurofibromas is difficult leading to incomplete resection and resurrence in most instances. Malignant transformation is likely to occur in plexiform neurofibromas. 

Prognosis in NF1 varies among individuals, given an equally varied course of illness. Life expectancy is 10  to 15 years, malignancy being the principal cause of death. The spectrum of illness includes brain tumors and malignant peripheral nerve sheath tumors. 

Types of neurofibromatosis: 

Neurofibromatosis type 1 (NF1) or von Recklinghausen disease is the most common type of neurofibromatosis, with prevalence rate of 1 in 2500 to 3000 persons worldwide. The disease involves neurologic, cutaneous, bone or soft-tissue structures in the body. NF1 (autosomal, dominant) gene appears on band 17q11.2, encoding for the synthesis of neurofibromin, a tumor suppressor. More than 1000 mutations have been identified, with germ cell mutation in 20 to 50% of cases.

Neurofibromatosis type 2 (NF2) occurs in 10% of neurofibromatosis cases, with prevalence rate of 1 in 35,000 persons. It causes vestibular schwannomas or congenital bilateral acoustic neuromas. NF2 gene appears on band 22q11, encoding for the synthesis of a tumor suppressor, merlin or schwannomin. The trait is inherited from one of the parents. Two hundred mutations have been reported.

Schwannomatosis is a rare disorder, constituting 15 % of neurofibromatosis cases. It occurs in families (that is, several members are affected). Germline mutation in the SMARCB1 gene is located at band 22q11.23, adjacent to the NF2 gene. Two or more schwannomas may be found in peripheral nerves, causing pain.

Neurofibroma affects persons 20 to 30 years old, male and female alike. The world incidence rate of neurofibromatosis type 1 (NF1, peripheral neurofibromatosis or von Recklinghausen disease) is between 1 in 2,500 to 1 in 3,000 individuals [4] [5]. Carriers of this autosomal dominant trait are prone to the occurrence of benign and malignant tumors which present with cafe-au-lait spots, fibromatous tumors in the skin and Lisch nodules in the eye.  

The central or type 2 neurofibromatosis (NF2) is an autosomal dominant gene that is linked to multiple neoplasia syndrome with incidence rate of 1 in 25,000 live births [6]. It is associated with meningiomas of the brain, tumors of the eighth cranial nerve (usually bilateral), and schwannomas of the dorsal roots of the spinal cord. NF2 is distinct from NF1. 

Neurofibromas are benign neoplasms consisting of schwann cells, fibroblasts  and abundant WHO grade 1 collagen fibres. In contrast to schwannomas, these are without capsules and can insinuate between nerve fascicles. Neurofibromas can potentially transform into malignant peripheral nerve sheath tumors (MPNST).

NF1 gene encodes for the synthesis of neurofibromin, belonging to a group of GTP-ase-activating proteins (GAPs) and which is found in the brain, thymus, spleen, and kidney [7] [8] [9]. GAPs stimulate intrinsic GTPase activity in the ras p21 family [10] [11] [12] which, in turn, activates the stem cell factor (SCF)/c-kit targeting rapamycin (mTOR), and mitogen-activated protein kinase (MAPK) pathways.

Mutations in the NF1 gene adversely affect the biosynthesis of functional proteins that could inhibit the development of NF1-associated tumors [9]. The NF1 trait varies within and among families [13]. Somatic and germline mutations account for complete loss of neurofibromin as in pseudoarthrosis [14] and neurofibromas [15]. Evidence indicates that NF1 is a tumor suppressor gene.

Neurofibromatosis type 2 (NF2) is attributed to defects in the NF2 gene, located on chromosome 22 [16]. NF2 normal cells produce merlin or schwannomin, a tumor suppressor [17] [18]. Molecular technology has made possible detection of abnormality in NF2 in over 93%  of families [19]. New mutations in NF2 manifested differently (somatic mosaicism) may be difficult to establish unless tumor tissue is analyzed [19] [20] [21] [22].

Mutations in NF2 gene means loss of ability to synthesize merlin. Tumor development presumes that both NF2 alleles are inactivated since tumors cannot develop in normal NF2 cell. An abnormal NF2 allele may be inherited from a heterogeneous parent. Thereafter, somatic mutation which may occur after fertilization, could result in two cell lines (mosaicism), one of which carrying the defective gene.

Neurofibromatosis is not preventable in the usual sense of the word. Even at that, the issue of prevention is an ethical one. It is a decision on whether or not to have a child if there is a potential for passing the hereditary condition based on family history. Nonetheless, genetic testing and counselling is recommended for prospective parents. 

Three types of neurofibromas:

• Localized neurofibroma is the most common type of neurofibroma, constituting 90% of all lesions. Most of these occur as single or solitary lesions which are not implicated in the pathogenesis of neurofibromatosis type 1 (NF1) [1].
• Diffuse neurofibroma presents as plaque-like, thickened, elevated lesions of the skin, 90% of which occur singly and are not associated with NF1 [2].
• Plexiform neurofibroma is pathognomonic of NF1 i.e., indicative of the disease condition caused by neurofibromatosis type 1 and that it is potentially malignant [3]. It involves a long nerve and its branches and extends into surrounding tissue beyond the epineurium.

Based on clinical and genetic origins, neurofibromatosis is further classified into: neurofibromatosis type 1 (NFI), type 2 (NF2) and schwannomatosis. NF1 or von Recklinghausen disease, is the most common type of neurofibroma. It is distinguished by the presence of multiple cafe-au-lait macules and neurofibromas. When confined to one location on the body, it is called segmental NF1.

The term "neurofibromatosis" is generic, that is, referring to several clinically related but genetically distinct disease entities. It is basically associated with the finding of benign or malignant tumors of the central or peripheral nervous system, often presenting with pigmented skin macules and other recognizable diagnostic features. Surgical removal is usually prescribed for benign tumors; radiation or chemotherapy for malignant cases.

Neurofibromas are benign tumors of the peripheral nerve sheath. These occur singly and infrequently, but in association with neurofibromatosis type 1 (NF1). The distinguishing features of NF1 are the multiple café-au-lait macules and concomitant skin tumors. Neurofibromas are the most commonly encountered benign tumors of type 1 neurofibromatosis. These tumors consist of mast cells, fibroblasts, Schwann cells, and vascular elements. Tumors are known to develop at any point along a nerve and have the potential to transform into malignant peripheral nerve sheath tumors (MPNST). At the moment curative treatment is not an option in neurofibromatosis. Research however aims to find appropriate medications to alleviate symptoms and to prevent recurrence. Surgical removal of the tumors provide relief in conjunction with radiation to reduce the size of the tumors. 

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