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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==

Revision as of 00:23, 30 April 2019

Neurofibroma Microchapters

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Overview

Historical Perspective

Classification

Pathophysiology

Causes

Differentiating Neurofibroma from other Diseases

Epidemiology and Demographics

Risk Factors

Screening

Natural History, Complications and Prognosis

Diagnosis

Diagnostic Study of Choice

Staging

History and Symptoms

Physical Examination

Laboratory Findings

X Ray

CT

MRI

Ultrasound

Other Imaging Findings

Other Diagnostic Studies

Treatment

Medical Therapy

Surgery

Primary Prevention

Secondary Prevention

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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). 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 cells 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 masses, 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 neurofibromas may progress to develop malignant peripheral nerve sheath tumor (MPNST).

Historical perspective

NF1-like cutaneous tumor syndromes appeared in the literature in 1880s, when Friedrich von Recklinghausen published seminal observations detailing cutaneoustumors comprised of both neuronal and fibroblastic tissue finally termed as neurofibromas. In 2006, Yang et al demonstrated a critical neurofibromamicroenvironment 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

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 cells 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.

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 tests such 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, neurologicaldeficits, 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.

Primary Prevention

There is no established method for prevention of neurofibroma.

Secondary Prevention

There are no secondary preventive measures available for neurofibroma.

References


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