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Neurofibroma

Summary

Neurofibroma is a benign lesion of unknown origin that may occur in the peripheral nerve, soft tissue, skin or bone. It occurs as a solitary lesion more commonly than as a multiple lesion or in neurofibromatosis (NF-1 or von Recklinghausen's disease). NF-1 is characterized by nuerofibromas, acoustic nerve schwannomas, Lisch nodules and cafe-au-lait spots.

Solitary lesions most commonly form in the brachial plexus, lumbrosacral plexus, peripheral nerve or spinal nerve.

They are most commonly present from age 20 to 30.
A Neurofibroma often arises as a superficial painless mass in the dermis.
On plain X-ray, it may appear as an intraosseous lytic lesion (if the neurofibroma involves the bone).
Complete Information on this Tumor
Introduction and Definition: 

Neurofibroma is a benign lesion of unknown origin that may occur in peripheral nerve, soft tissue, skin or bone. It occurs as a solitary lesion more commonly than as a multiple lesion or in neurofibromatosis (NF-1 or von Recklinghausen's disease). NF-1 is characterized by neurofibromas, acoustic nerve schwannomas, Lisch nodules and cafe-au-lait spots. Neurofibromas that occur as part of von Recklinghausen's disease are generally larger than solitary lesions and have a 4% chance of malignant transformation.

Incidence and Demographics: 
Neurofibromas occur more commonly in patients aged 20 to 30.
Symptoms and Presentation: 

They often arise as superficial painless masses in the dermis.

X-Ray Appearance and Advanced Imaging Findings: 
On plain x-ray, if the neurofibroma involves the bone it may appear as an intraosseous lytic lesion. The lesion visible on plain film may be a neurofibroma that has worked into the bone by pressure erosion or it may be a non-ossifying fibroma that is associated with NF-1. On ultrasound, a neurofibroma is a well-defined hypoechoic mass. On CT scan, a neurofibroma is a hypodense, well-defined mass. On a T2 weighted MRI the lesion is bright and may have a central low density which gives a "target" appearance. The lesion appears hyperintense on T1 weighted MRI. The term "dumbbell" lesion is used to describe a neurofibroma that is enlarging the intervertebral foramen.
Laboratory Findings: 
On gross appearance, a neurofibroma is a firm, gray-white mass with no capsule. They vary in size from a few millimeters to four to five centimeters.
Histopathology findings: 
Microscopically, neurofibromas are made of interlacing bundles of elongated cells. These cells are bland and disorderly with intracellular collagen strands. Neurofibromas have variable S-100 expression and nerve fibers should be present. There are two types of neurofibromas: solitary and plexiform. Solitary neurofibromas are well delineated, firm lesions that are white and shiny in appearance. Plexiform neurofibromas are multifocal myxoid lesions that are often described as a "bag of worms". Plexiform neurofibromas are diagnostic of von Recklinghausen's disease.
Treatment Options for this Tumor: 
Patients with NF-1 should perform regular self-exams to detect tumors early. Close follow up of these patients is necessary due to the high rate of malignant transformation. Treatment, if necessary, is surgical excision.
Outcomes of Treatment and Prognosis: 
Following any procedures, it is imperative that patients perform self-examinations to detect any future tumors early.
Suggested Reading and Reference: 
Beggs, I, Pictorial Review: Imaging of Peripheral Nerve Tumors, Clinical Radiology, 52:8-17,1997. Bulloughs, Peter, Orthopaedic Pathologv (third edition), Times Mirror International Publishers Limited, London, 1997. Cotran, Robbins and Kumar, Robbins Pathologic Basis for Disease, W.B. Saunders, Co., 1994. Huvos, Andrew, Bone Tumors:Diagnosis. Treatment and Prognosis, W.B. Saunders, Co., 1991.