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{{CMG}}; {{AE}}{{S.M.}}, {{SC}}
{{CMG}}; {{AE}}{{S.M.}}, {{SC}}
==Overview==
==Overview==
Neurofibromas are benign [[nerve sheath tumor|nerve sheath tumors]] of neural origin in peripheral nervous system, comprising all elements of the peripheral nerve (i.e. axons, Schwann cells and fibroblasts). Neurofibromas may occur as part of the syndrome of neurofibromatosis (commonest), solitary neurofibromas, or multiple neurofibromas without von Recklinghausen's disease (NF-1). Neurofibroma may be classified into 3 subtypes: localised neurofibroma, diffuse neurofibroma, and [[plexiform neurofibroma]]. On gross pathology, a nonencapsulated superficial [[mass]] is the characteristic finding of localised or diffuse neurofibroma; whereas the "bag of worms" appearance is the characteristic finding of [[plexiform neurofibroma]]. On microscopic histopathological analysis, [[spindle cell]]s with wavy [[nuclei]] without pleomorphism, wire-like [[collagen]], moderate increase of cellularity vis-a-vis normal [[dermis]], and [[mast cells]] are characteristic findings of neurofibroma. [[Plexiform neurofibroma]] may be caused by the bi-allelic inactivation of the [[neurofibromatosis type I]] tumor suppressor gene. Neurofibroma must be differentiated from [[schwannoma]], [[dermatofibrosarcoma protuberans]] (DFSP), [[ganglioneuroma]], and [[melanocytic nevus]]. Neurofibroma usually affects individuals between 20 and 30 years of age. Neurofibroma affects men and women equally. Symptoms of neurofibroma include soft [[mass]]es, transient [[itching]], and transient [[pain]]. [[Biopsy]] is helpful in the diagnosis of neurofibroma. The predominant therapy for neurofibroma is surgical resection. Adjunctive [[chemotherapy]] and medications may be required. [[Prognosis]] of neurofibroma is generally excellent. If left untreated, 10% of patients with [[plexiform neurofibroma]]s may progress to develop [[malignant peripheral nerve sheath tumor]] (MPNST).  
[[Neurofibroma|Neurofibromas]] are [[benign]] [[nerve sheath tumor|nerve sheath tumors]] of [[neural]] [[origin]] in [[peripheral nervous system]], comprising all [[Element|elements]] of the [[peripheral nerve]] (i.e. [[axons]], [[Schwann cells]] and [[fibroblasts]]) and can occur anywhere in the [[body]]. [[Neurofibroma|Neurofibromas]] may occur as part of the [[syndrome]] of [[neurofibromatosis]] (most common), [[solitary]] [[Neurofibroma|neurofibromas]], or multiple [[Neurofibroma|neurofibromas]] without [[von Recklinghausen's disease]] ([[NF-1]]). [[Neurofibroma]] may be [[Classification|classified]] into further subtypes such as localized, [[cutaneous]], [[subcutaneous]], intraneural, [[intramuscular]], [[diffuse]], [[Pigmented Lesions|pigmented]], and [[plexiform neurofibroma]]. However, [[plexiform neurofibroma]] can be further subclassified into [[diffuse]], and [[nodular]] [[plexiform neurofibroma]]. [[Gene]] involved in the [[pathogenesis]] of [[plexiform neurofibroma]] is ''[[Neurofibromatosis type I|NF1]]'' which [[Code|codes]] for [[neurofibromin]] that leads to loss of ''[[RAS]]'' [[control]] causing increased [[Activity (chemistry)|activity]] of [[Downstream (molecular biology)|downstream]] [[RAS]] pathways involved in increased [[Cell (biology)|cell]] [[growth]] and [[Survival rate|survival]]. On [[gross pathology]], a non-encapsulated [[superficial]] [[mass]] is the characteristic finding of localized or [[diffuse]] [[neurofibroma]]; whereas the "bag of worms" [[appearance]] is the characteristic finding of [[plexiform neurofibroma]]. On [[microscopic]] [[histopathological]] [[analysis]], [[nerve fibers]], [[schwann cells]], [[spindle cell]]s with wavy [[nuclei]] without [[pleomorphism]], shredded carrot [[collagen]], moderate increase of cellularity vis-a-vis normal [[dermis]], [[blood vessels]], [[mast cells]], pseudomeissnerian [[Body|bodies]], and varying [[Degree (angle)|degrees]] of myxoid [[degeneration]] are characteristic findings of [[neurofibroma]]. However, [[plexiform neurofibroma]] shows a characteristic target [[Sign (medicine)|sign]] on [[Histopathology|histopathology.]] It usually [[Affect|affects]] both [[men]] and women equally between the [[age]] of 20-40 years. Common [[symptoms]] of [[neurofibroma]] include [[Soft tissue|soft]] [[mass]]es, transient [[itching]], and transient [[pain]] with rest of the [[symptoms]] depending upon the involved site. There is no single [[diagnostic study of choice]] for [[neurofibroma]], instead, it is [[Diagnose|diagnosed]] on the basis of [[medical history]], [[physical examination]], and [[imaging studies]] such as [[Computed tomography|CT]] or [[Magnetic resonance imaging|MRI]]. The predominant [[therapy]] for [[neurofibroma]] is [[surgical resection]]. Adjunctive [[chemotherapy]] and [[medications]] such as [[ACE inhibitor|ACE inhibitors]] may be required. [[Prognosis]] of [[neurofibroma]] is generally excellent. If left untreated, 10% of [[patients]] with [[plexiform neurofibroma]]s may progress to develop [[malignant peripheral nerve sheath tumor]] ([[MPNST]]). [[Local]] [[Recurrence plot|recurrence]] occurs [[Rare|rarely]].
 
==Historical Perspective==
==Historical perspective==
[[NF-1|NF1]]-like [[cutaneous]] [[tumor]] [[syndromes]] appeared in the [[Literature review|literature]] in 1880s, when Friedrich [[Von Recklinghausen's Disease|von Recklinghausen]] published seminal [[Observation|observations]] detailing [[cutaneous]] [[tumors]] comprised of both [[Neuron|neuronal]] and [[Fibroblast|fibroblastic tissue]] finally termed as [[Neurofibroma|neurofibromas]]. In 2006, Yang et al demonstrated a critical [[neurofibroma]] microenvironment [[interaction]] that includes [[SCF-complex|SCF]]-[[Stimulated emission|stimulated]] [[NF-1|Nf1]]+/− [[mast cells]] [[Potentiator|potentiating]] [[NF-1|Nf1]]+/− [[fibroblast]] [[Function (biology)|functions]].
[[NF-1|NF1]]-like [[cutaneous]] [[tumor]] [[syndromes]] appeared in the [[Literature review|literature]] in 1880s, when Friedrich [[Von Recklinghausen's Disease|von Recklinghausen]] published seminal [[Observation|observations]] detailing [[cutaneous]][[tumors]] comprised of both [[Neuron|neuronal]] and [[Fibroblast|fibroblastic tissue]] finally termed as [[Neurofibroma|neurofibromas]]. In 2006, Yang et al demonstrated a critical [[neurofibroma]]<nowiki/>microenvironment [[interaction]] that includes [[SCF-complex|SCF]]-[[Stimulated emission|stimulated]] [[NF-1|Nf1]]+/− [[mast cells]] [[Potentiator|potentiating]] [[NF-1|Nf1]]+/− [[fibroblast]] [[Function (biology)|functions]].
 
==Classification==
==Classification==
[[Neurofibroma]] may be [[Classification|classified]] into 5 subtypes: [[cutaneous]]/[[dermal]]/[[Localized disease|localized]], localized intraneural, [[subcutaneous]], [[diffuse]], [[intramuscular]], [[Plexiform neurofibroma|plexiform]] and [[Pigmented lesions|pigmented]] [[neurofibroma]]. [[Plexiform neurofibroma|Plexiform neurofibromas]] may be further [[Subclass (biology)|sub-classified]] into [[diffuse]] and [[nodular]] [[Plexiform neurofibroma|plexiform]].
[[Neurofibroma]] may be [[Classification|classified]] into 5 subtypes: [[cutaneous]]/[[dermal]]/[[Localized disease|localized]], localized intraneural, [[subcutaneous]], [[diffuse]], [[intramuscular]], [[Plexiform neurofibroma|plexiform]] and [[Pigmented lesions|pigmented]] [[neurofibroma]]. [[Plexiform neurofibroma|Plexiform neurofibromas]] may be further [[Subclass (biology)|sub-classified]] into [[diffuse]] and [[nodular]] [[Plexiform neurofibroma|plexiform]].


==Pathophysiology==
==Pathophysiology==
On gross pathology, a nonencapsulated superficial [[mass]] is the characteristic finding of localised or diffuse neurofibroma; whereas the "bag of worms" appearance is the characteristic finding of [[plexiform neurofibroma]]. On microscopic histopathological analysis, [[spindle cell]]s with wavy [[nuclei]] without pleomorphism, wire-like [[collagen]], moderate increase of cellularity vis-a-vis normal [[dermis]], and [[mast cells]] are characteristic findings of neurofibroma.
[[Neurofibroma|Neurofibromas]] arise from the nonmyelinating-type [[Schwann cells]]. [[Gene]] involved in the [[pathogenesis]] of [[plexiform neurofibroma]] is ''[[Neurofibromatosis type I|NF1]]'' which [[Code|codes]] for [[neurofibromin]] that leads to loss of ''[[RAS]]'' [[control]] causing increased [[Activity (chemistry)|activity]] of [[Downstream (molecular biology)|downstream]] [[RAS]] pathways involved in increased [[Cell (biology)|cell]] [[growth]] and [[Survival rate|survival]]. [[Neurofibroma|Neurofibromas]] can occur anywhere in [[body]]. On [[gross pathology]], a nonencapsulated [[superficial]] [[mass]] is the characteristic finding of localised or [[diffuse]][[neurofibroma]]; whereas the "bag of worms" [[appearance]] is the characteristic finding of [[plexiform neurofibroma]]. On [[microscopic]] [[histopathological]] [[analysis]], [[nerve fibers]], [[schwann cells]], [[Spindle cell|spindle cells]] with wavy [[nuclei]] without [[pleomorphism]], shredded carrot [[collagen]], moderate increase of cellularity vis-a-vis normal [[dermis]], [[blood vessels]], [[mast cells]], pseudomeissnerian [[Body|bodies]], and varying [[Degree (angle)|degrees]] of myxoid [[degeneration]] are characteristic findings of [[neurofibroma]]. However, [[plexiform neurofibroma]] shows a characteristic target [[Sign (medicine)|sign]] on [[Histopathology|histopathology,]] representing a [[central]] [[Core (anatomy)|core]] of [[collagenous]] and [[Fibril|fibrillary]] [[Tissue (biology)|tissue]] with [[Periphery|peripheral]] less [[Dense|densely]][[cellular]] myxoid [[Tissue (biology)|tissue]]. [[Electron microscopy]] of [[Neurofibroma|neurofibromas]] shows [[Schwann cells]] enclosing [[axons]] in plasmalemmal [[Invagination|invaginations]] (mesaxons).


==Causes==
==Causes==
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==Natural History, Complications and Prognosis==
==Natural History, Complications and Prognosis==
[[Prognosis]] of neurofibroma is generally excellent. If left untreated, 10% of patients with [[Plexiform neurofibroma|plexiform neurofibromas]] may progress to develop [[malignant peripheral nerve sheath tumor]] (MPNST). Local recurrence occurs rarely.  
[[Prognosis]] of [[neurofibroma]] is generally excellent. If left untreated, 10% of [[patients]] with [[Plexiform neurofibroma|plexiform neurofibromas]] may progress to develop [[malignant peripheral nerve sheath tumor]] ([[MPNST]]). [[Local]] [[Recurrence plot|recurrence]] occurs [[Rare|rarely]].  


==Diagnosis==
==Diagnosis==
===Diagnostic Study of Choice===
===Diagnostic Study of Choice===
There is no single diagnostic study of choice for neurofibroma, instead, it is diagnosed on the basis of medical history, physical examination, and imaging tests such as CT or MRI.
There is no single [[diagnostic study of choice]] for [[neurofibroma]], instead, it is [[Diagnose|diagnosed]] on the basis of [[medical history]], [[physical examination]], and [[imaging studies]]<nowiki/>such as [[Computed tomography|CT]] or [[Magnetic resonance imaging|MRI]].
===Staging===
===Staging===
There is no established system for the staging of neurofibroma.
There is no established [[system]] for the [[Cancer staging|staging]] of [[neurofibroma]].
===History and symptoms===
===History and symptoms===
[[Neurofibroma|Neurofibromas]] can form anywhere in [[Human body|body]] with [[diffuse]] [[Neurofibroma|neurofibromas]] commonly involving [[scalp]]. [[Symptoms]] of [[neurofibroma]] include soft [[Mass|masses]]/[[Bumps on skin|bumps]] ([[internal]] or [[superficial]]) , [[transient]] [[itching]], [[pain]], [[numbness]] and [[tingling]] in the affected [[area]], severe [[bleeding]], [[Physical therapy|physical]] disfiguration, [[cognitive]] [[disability]], [[Stinging in the eye|stinging]], [[neurological]][[Deficits in Attention, Motor control and Perception|deficits]], [[Change detection|changes]] in [[Movement disorder|movement]] ([[clumsiness]] in the [[hands]], trouble [[walking]]), [[bowel]] [[Bladder incontinence|incontinence]], [[scoliosis]], UTI, urinary retention, urgency, frequency, urinary incontinence, hematuria, hydronephrosis, or pelvic mass.
[[Neurofibroma|Neurofibromas]] can form anywhere in [[Human body|body]] with [[diffuse]] [[Neurofibroma|neurofibromas]] commonly involving [[scalp]]. [[Symptoms]] of [[neurofibroma]] include soft [[mass]]es/[[Bumps on skin|bumps]] ([[internal]] or [[superficial]]) , [[transient]] [[itching]], [[pain]], [[numbness]] and [[tingling]] in the affected [[area]], severe [[bleeding]], [[Physical therapy|physical]] disfiguration, [[cognitive]] [[disability]], [[Stinging in the eye|stinging]], [[neurological]] [[Deficits in Attention, Motor control and Perception|deficits]], [[Change detection|changes]] in [[Movement disorder|movement]] ([[clumsiness]] in the [[hands]], trouble [[walking]]), [[bowel]] [[Bladder incontinence|incontinence]], [[scoliosis]], [[UTI]], [[urinary retention]], [[urgency]], [[frequency]], [[urinary incontinence]], [[hematuria]], [[hydronephrosis]], or [[Pelvic masses|pelvic mass]].


===Physical Examination===
===Physical Examination===
Physical examination of patients with neurofibroma is usually remarkable for soft [[mass]]es (internal or superficial).
[[Physical examination]] of [[patients]] with [[neurofibroma]] is usually remarkable for [[Soft tissue|soft]] [[Mass|masses]] ([[Internal|interna]]<nowiki/>l or [[superficial]]).


===Laboratory Findings===
===Laboratory Findings===
On [[Immunohistochemistry]], [[neurofibroma]] stains positive for [[S100A1|S100]], SOX10, [[CD34]], factor XIIIa, [[neurofilament]], [[GFAP]] and [[calretinin]] and negative for EMA, [[keratin]], smooth muscle actin, [[desmin]], [[calponin]], [[caldesmon]] and [[p53]].
On [[Immunohistochemistry]], [[neurofibroma]] [[Stain|stains]] positive for [[S100A1|S100]], [[SOX10]], [[CD34]], factor XIIIa, [[neurofilament]], [[GFAP]] and [[calretinin]] and negative for EMA, [[keratin]], [[smooth muscle]] [[actin]], [[desmin]], [[calponin]], [[caldesmon]] and [[p53]].


===X Ray===
===X Ray===
There are no [[X-ray]] findings associated with neurofibroma.
There are no [[X-ray]] findings associated with [[neurofibroma]].


===CT Scan===
===CT Scan===
[[CT scan]] may be helpful in the diagnosis of neurofibroma. Findings on CT scan suggestive of neurofibroma include a well-defined, round or oval hypodense, fusiform [[mass]] representing the nerve entering and exiting the tumor. Low attenuation is attributed to high lipid or water content within the mucinous matrix, entrapment of perineural adipose tissue and cystic degeneration.
[[CT scan]] may be helpful in the [[diagnosis]] of [[neurofibroma]]. Findings on [[Computed tomography|CT scan]] suggestive of [[neurofibroma]] include a well-defined, round or [[oval]] hypodense, [[fusiform]] [[mass]] representing the [[nerve]] entering and exiting the [[tumor]]. Low [[attenuation]] is attributed to high [[lipid]] or [[water]] content within the [[mucinous]] [[matrix]], entrapment of perineural [[adipose tissue]] and [[cystic]] [[degeneration]].


===MRI===
===MRI===
[[MRI]] may be helpful in the diagnosis of neurofibroma. It appears as a hypointense, homogeneous low signal intensity lesion with center demonstrating a higher signal intensity than the periphery on T1. T2 weighted images show hyperintense, homogeneous lesion with positive target sign and fascicular sign. Moreover, neurofibromas have heterogeneous enhancement on T1 C+ (Gd) (with gadolinium contrast).
[[MRI]] may be helpful in the [[diagnosis]] of [[neurofibroma]]. It [[Appearance|appears]] as a hypointense, [[homogeneous]] low [[Signal (biology)|signal]] [[intensity]] [[lesion]] with center demonstrating a higher [[Signal (biology)|signal]] [[intensity]] than the [[periphery]] on [[T1]]. T2 [[Weighted mean|weighted]] [[images]] show hyperintense, [[homogeneous]] [[lesion]] with positive [[Target cell|target]] [[Sign (medicine)|sign]] and [[Fascicle|fascicular]] [[Sign (medicine)|sign]]. Moreover, [[Neurofibroma|neurofibromas]] have [[heterogeneous]] enhancement on [[T1]] C+ (Gd) (with [[gadolinium]] [[contrast]]).


===Ultrasound===
===Ultrasound===
There are no [[ultrasound]] findings associated with neurofibroma.
There are no [[ultrasound]] findings associated with [[neurofibroma]].


===Other Imaging Findings===
===Other Imaging Findings===
There are no other imaging findings associated with neurofibroma.
There are no other [[imaging]] findings associated with [[neurofibroma]].


===Other Diagnostic Studies===
===Other Diagnostic Studies===
There are no other diagnostic study findings associated with neurofibroma.
There are no other [[Diagnostic study of choice|diagnostic study]] findings associated with [[neurofibroma]].


===Biopsy===
===Biopsy===
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==Treatment==
==Treatment==
===Medical Therapy===
===Medical Therapy===
The predominant therapy for neurofibroma is [[surgical resection]]. Adjunctive [[chemotherapy]] and medications such as ACE inhibitors may be required.
The predominant [[therapy]] for [[neurofibroma]] is [[surgical resection]]. Adjunctive [[chemotherapy]] and [[medications]] such as [[ACE inhibitor|ACE inhibitors]] may be required.


===Surgery===
===Surgery===
[[Surgery]] is the mainstay of treatment for neurofibroma.
[[Surgery]] is the mainstay of treatment for [[neurofibroma]]. Localized and [[diffuse]] [[lesions]] are usually treated [[Surgery|surgically]]. [[Neurofibroma|Neurofibromas]] that [[Infiltration (medical)|infiltrate]] between [[nerve]][[fascicles]] are unable to be separated from the parent [[nerve]], therefore, deep-seated [[lesions]] are often [[Managed Care|managed]] conservatively. Local [[Recurrence plot|recurrence]] after [[excision]] is uncommon .and [[malignant transformation]] occurs [[Rare|rarely]].


===Primary Prevention===
===Primary Prevention===
There is no established method for prevention of neurofibroma.
There is no established method for [[primary prevention]] of [[neurofibroma]].


===Secondary Prevention===
===Secondary Prevention===
There are no secondary preventive measures available for neurofibroma.
There are no [[Secondary prevention|secondary preventive measures]] available for [[neurofibroma]].


==References==
==References==

Latest revision as of 16:59, 1 November 2019

Neurofibroma Microchapters

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Sara Mohsin, M.D.[2], Shanshan Cen, M.D. [3]

Overview

Neurofibromas are benign nerve sheath tumors of neural origin in peripheral nervous system, comprising all elements of the peripheral nerve (i.e. axons, Schwann cells and fibroblasts) and can occur anywhere in the body. Neurofibromas may occur as part of the syndrome of neurofibromatosis (most common), solitary neurofibromas, or multiple neurofibromas without von Recklinghausen's disease (NF-1). Neurofibroma may be classified into further subtypes such as localized, cutaneous, subcutaneous, intraneural, intramuscular, diffuse, pigmented, and plexiform neurofibroma. However, plexiform neurofibroma can be further subclassified into diffuse, and nodular plexiform neurofibroma. Gene involved in the pathogenesis of plexiform neurofibroma is NF1 which codes for neurofibromin that leads to loss of RAS control causing increased activity of downstream RAS pathways involved in increased cell growth and survival. On gross pathology, a non-encapsulated superficial mass is the characteristic finding of localized or diffuse neurofibroma; whereas the "bag of worms" appearance is the characteristic finding of plexiform neurofibroma. On microscopic histopathological analysis, nerve fibers, schwann cells, spindle cells with wavy nuclei without pleomorphism, shredded carrot collagen, moderate increase of cellularity vis-a-vis normal dermis, blood vessels, mast cells, pseudomeissnerian bodies, and varying degrees of myxoid degeneration are characteristic findings of neurofibroma. However, plexiform neurofibroma shows a characteristic target sign on histopathology. It usually affects both men and women equally between the age of 20-40 years. Common symptoms of neurofibroma include soft masses, transient itching, and transient pain with rest of the symptoms depending upon the involved site. There is no single diagnostic study of choice for neurofibroma, instead, it is diagnosed on the basis of medical history, physical examination, and imaging studies such as CT or MRI. The predominant therapy for neurofibroma is surgical resection. Adjunctive chemotherapy and medications such as ACE inhibitors may be required. Prognosis of neurofibroma is generally excellent. If left untreated, 10% of patients with plexiform neurofibromas may progress to develop malignant peripheral nerve sheath tumor (MPNST). Local recurrence occurs rarely.

Historical Perspective

NF1-like cutaneous tumor syndromes appeared in the literature in 1880s, when Friedrich von Recklinghausen published seminal observations detailing cutaneous tumors comprised of both neuronal and fibroblastic tissue finally termed as neurofibromas. In 2006, Yang et al demonstrated a critical neurofibroma microenvironment interaction that includes SCF-stimulated Nf1+/− mast cells potentiating Nf1+/− fibroblast functions.

Classification

Neurofibroma may be classified into 5 subtypes: cutaneous/dermal/localized, localized intraneural, subcutaneous, diffuse, intramuscular, plexiform and pigmented neurofibroma. Plexiform neurofibromas may be further sub-classified into diffuse and nodular plexiform.

Pathophysiology

Neurofibromas arise from the nonmyelinating-type Schwann cells. Gene involved in the pathogenesis of plexiform neurofibroma is NF1 which codes for neurofibromin that leads to loss of RAS control causing increased activity of downstream RAS pathways involved in increased cell growth and survival. Neurofibromas can occur anywhere in body. On gross pathology, a nonencapsulated superficial mass is the characteristic finding of localised or diffuseneurofibroma; whereas the "bag of worms" appearance is the characteristic finding of plexiform neurofibroma. On microscopic histopathological analysis, nerve fibers, schwann cells, spindle cells with wavy nuclei without pleomorphism, shredded carrot collagen, moderate increase of cellularity vis-a-vis normal dermis, blood vessels, mast cells, pseudomeissnerian bodies, and varying degrees of myxoid degeneration are characteristic findings of neurofibroma. However, plexiform neurofibroma shows a characteristic target sign on histopathology, representing a central core of collagenous and fibrillary tissue with peripheral less denselycellular myxoid tissue. Electron microscopy of neurofibromas shows Schwann cells enclosing axons in plasmalemmal invaginations (mesaxons).

Causes

Plexiform neurofibroma may be caused by the bi-allelic inactivation of the neurofibromatosis type I tumor suppressor gene.

Differential Diagnosis

Neurofibroma must be differentiated from schwannoma, dermatofibrosarcoma protuberans (DFSP), ganglioneuroma, dermal neurotized melanocytic nevus, myxoid liposarcoma, solitary circumscribed neuroma, traumatic neuroma, superficial angiomyxoma, nerve sheath myxoma, malignant peripheral nerve sheath tumor, spindle cell lipoma, leiomyoma, inflammatory myofibroblastic tumor, and fibroepithelial polyp.

Epidemiology and Demographics

Neurofibroma usually occurs between 20-40 years of age, and affects men and women equally. However, plexiform neurofibromas are thought to be congenital defects, hence, they occur earlier in life.

Risk Factors

Neurofibromatosis 1 and Neurofibromatosis 2 are the most common risk factors for development of neurofibromas.

Screening

According to the the U.S. Preventive Service Task Force (USPSTF), there is insufficient evidence to recommend routine screening for neurofibroma.

Natural History, Complications and Prognosis

Prognosis of neurofibroma is generally excellent. If left untreated, 10% of patients with plexiform neurofibromas may progress to develop malignant peripheral nerve sheath tumor (MPNST). Local recurrence occurs rarely.

Diagnosis

Diagnostic Study of Choice

There is no single diagnostic study of choice for neurofibroma, instead, it is diagnosed on the basis of medical history, physical examination, and imaging studiessuch as CT or MRI.

Staging

There is no established system for the staging of neurofibroma.

History and symptoms

Neurofibromas can form anywhere in body with diffuse neurofibromas commonly involving scalp. Symptoms of neurofibroma include soft masses/bumps (internal or superficial) , transient itching, pain, numbness and tingling in the affected area, severe bleeding, physical disfiguration, cognitive disability, stinging, neurological deficits, changes in movement (clumsiness in the hands, trouble walking), bowel incontinence, scoliosis, UTI, urinary retention, urgency, frequency, urinary incontinence, hematuria, hydronephrosis, or pelvic mass.

Physical Examination

Physical examination of patients with neurofibroma is usually remarkable for soft masses (internal or superficial).

Laboratory Findings

On Immunohistochemistry, neurofibroma stains positive for S100, SOX10, CD34, factor XIIIa, neurofilament, GFAP and calretinin and negative for EMA, keratin, smooth muscle actin, desmin, calponin, caldesmon and p53.

X Ray

There are no X-ray findings associated with neurofibroma.

CT Scan

CT scan may be helpful in the diagnosis of neurofibroma. Findings on CT scan suggestive of neurofibroma include a well-defined, round or oval hypodense, fusiform mass representing the nerve entering and exiting the tumor. Low attenuation is attributed to high lipid or water content within the mucinous matrix, entrapment of perineural adipose tissue and cystic degeneration.

MRI

MRI may be helpful in the diagnosis of neurofibroma. It appears as a hypointense, homogeneous low signal intensity lesion with center demonstrating a higher signal intensity than the periphery on T1. T2 weighted images show hyperintense, homogeneous lesion with positive target sign and fascicular sign. Moreover, neurofibromas have heterogeneous enhancement on T1 C+ (Gd) (with gadolinium contrast).

Ultrasound

There are no ultrasound findings associated with neurofibroma.

Other Imaging Findings

There are no other imaging findings associated with neurofibroma.

Other Diagnostic Studies

There are no other diagnostic study findings associated with neurofibroma.

Biopsy

Biopsy is helpful in the diagnosis of neurofibroma.

Treatment

Medical Therapy

The predominant therapy for neurofibroma is surgical resection. Adjunctive chemotherapy and medications such as ACE inhibitors may be required.

Surgery

Surgery is the mainstay of treatment for neurofibroma. Localized and diffuse lesions are usually treated surgically. Neurofibromas that infiltrate between nervefascicles are unable to be separated from the parent nerve, therefore, deep-seated lesions are often managed conservatively. Local recurrence after excision is uncommon .and malignant transformation occurs rarely.

Primary Prevention

There is no established method for primary prevention of neurofibroma.

Secondary Prevention

There are no secondary preventive measures available for neurofibroma.

References


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