Learn all about Plexiform Neurofibroma and its symptoms and treatments. Plexiform Neurofibroma is a benign tumor of peripheral nerves arising from a proliferation of all neural elements. Plexiform neurofibromas are present at birth, but may not be identified until later. Non-plexiform neurofibromas usually appear during the teenage and adult years. According to the World Health Organization classification system, dermal and plexiform neurofibromas are grade-1 tumors.
According to clinical presentation it is a subcutaneous mass which feels like a “bag of worms”. Most of the time, it is a superficial cutaneous/subcutaneous lesion, but it can occur almost anywhere in the body. Symptoms may be related to local mass effect. Studies say that about 30% of people diagnosed with Neurofibromatosis, have these types of tumors, affecting them in many different ways. There is a risk of malignant transformation in 5-10% of cases.
Plexiform neurofibromas may cause a marked deformation and enlargement of a body part or region, an event known as elephantiasis neuromatosa. Often congenital Lesions are composed of sheets of neurofibromatous tissue that may infiltrate and encase major nerves, blood vessels, and other vital structures. Plexiform neurofibroma can cause disfigurement, neurological and other clinical deficits. Plexiform neurofibromas have the potential to cause severe clinical complications if they occur in certain areas.
Plexiform neurofibromas occur earlier in life and are thought to be congenital defects. Plexiform neurofibromas may cause a marked deformation and enlargement of a body part or region, an event known as elephantiasis neuromatosa. Although these tumors tend to grow slowly, they may grow to an enormous size and can cause serious disfigurement, brain dysfunction, or impingement on other organs. They may also cause pain. The tumors can cause severe pain, numbness, tingling, and/or weakness in the toes and fingers.
About 10% of plexiform neurofibromas undergo transformation into a malignant peripheral nerve sheath tumor (MPNST). In 2002, the primary treatment option for plexiform neurofibroma was surgery. Removal of plexiform neurofibromas is difficult because they can be large and cross tissue boundaries. However, besides pain, plexiform neurofibromas are sometimes removed due to the possibility of malignant transformation. Once a plexiform neurofibroma has undergone malignant transformation, radiation and chemotherapy can be used as treatment. However, radiation is generally not used as a treatment for plexiform neurofibromas because of concerns that this could actually promote malignant transformation.
What is Plexiform Neurofibroma?
The term Plexiform comes from the infiltrative growth pattern that, histologically, looks like a plexus or a network. It is typically associated with tumors of neural derivation. Plexiform neurofibromas are considered the prototype of the plexiform pattern. Plexiform Neurofibroma is a type of lesion, representing an anomaly rather than a true neoplasm, in which the proliferation of Schwann cells occurs from the inner aspect of the nerve sheath. In other words it is a benign, non-encapsulated tumour composed of proliferating axons, Schwann cells, fibroblasts and perineurial cells. Plexiform neurofibromas can grow from nerves in the skin or from more internal nerve bundles, and can be very large. Internal plexiform neurofibromas are very difficult to remove completely because they extend through multiple layers of tissue and the attempt would damage healthy tissue or organs. Plexiform Neurofibromas are ill-defined (meaning they are not round and typically grow deep within tissue and bone).
Plexiform Neurofibroma Treatment
Plexiform Neurofibroma treatments include surgeries to remove tumors, stereotactic radiosurgeries and auditory brainstem implants and cochlear implants. There is no cure for neurofibromatosis and the goal of treatment is to relieve symptoms. Painful cutaneous and subcutaneous tumors and those that occur on visible areas of the body may be removed surgically. Pain medications are also used to get relief from pain.
Doctors may prescribe Gabapentin (Neurotin) or pregabalin (Lyrica) for nerve pain. Other medications include;
- Tricyclic antidepressants such as amitriptyline may also be prescribed.
- Serotonin and norepinephrine reuptake inhibitors such as duloxetine (Cymbalta).
- Epilepsy medications such as topiramate (Topamax) or carbamazepine (Carbatrol, Tegretol).
Plexiform Neurofibroma Symptoms
Plexiform Neurofibroma symptoms generally appear in the late teen and early adult years, and can vary in severity. Some of the symptoms of plexiform neurofibroma are;
- Gradual hearing loss
- Ringing in the ears
- Poor balance
- Numbness and weakness in the arms or legs
- Balance difficulties
- Facial drop
- Vision problems or the development of cataracts
- specific abnormality of arm bone (radial dysplasia) or leg bone (tibial dysplasia)
- freckling in the armpit, groin or neck folds
- Tiny bumps on the iris of your eye (Lisch nodules)
- Soft bumps on or under the skin (neurofibromas)
- Learning disabilities
- Loss of muscle