Definition and Diagnosis

Plexiform neurofibromas are extensive nerve sheath tumors that can become quite large in size. They occur in patients with neurofibromatosis type 1, and present as large soft tissue masses under the skin. Occasionally, these tumors can become malignant. This is heralded by rapid growth and pain. MRI with and without contrast fully defines these tumors. PET scans may be used to help exclude malignancy.

MRI revealing an extensive plexiform neurofibroma that has replaced the right gluteus maximus (asterisk)

Treatment Options

These tumors often surround vital nerves, vessels, and joints. Therefore, they are not usually curable with surgery. If they become cosmetically unacceptable, or irritate nearby nerves, they can be partially removed. Because patients with neurofibromatosis type 1 often have multiple plexiform neurofibromas that cannot be completely excised without significant risk to nearby nerves, surgery is rarely recommended. If there is any suspicion of malignancy, an immediate biopsy and/or removal can be performed.