Orbital Tumors - Neurofibroma

Description of Orbital Neurofibroma

  • Orbital neurofibroma is a peripheral nerve sheath neoplasm derived from Schwann cells, perineural cells and fibroblasts, and is probably {the} most common peripheral nerve tumour of {the} orbit. It constitutes about 0.8 to 3.0% of all histopathologically-proven lesions of {the} orbit. Orbital neurofibroma produce symptoms within {the} orbit, and may possibly or may possibly not be associated with systemic neurofibromatosis.

Orbital neurofibroma is classified into three subsets:

  1. Plexiform neurofibroma is pathognomonic of neurofibromatosis.
  2. Diffuse nerofibroma has variable association with neurofibromatosis.
  3. Localized neurofibroma is rarely associated with neurofibromatosis.

Symptoms and Signs of Orbital Neurofibroma

  • The presence of multiple painful, well-circumscribed orbital tumours in a patient should raise {the} suspicion of neurofibroma. Typically, it presents with progressive symptoms of an orbital mass, including proptosis, globe displacement, impaired extraocular motility, ptosis, numbness, and rarely with decreased visual acuity. There may possibly also be associated features of neurofibromatosis. The clinical features of orbital neurofibroma is greatly dependent on its type and associated neurofibromatosis.
  • Plexiform orbital neurofibroma: The patient is usually a child in {the} originally decade of life with undeniable signs of neurofibromatosis, with about 66% having eyelid involvement. It usually begins as an eyelid mass that is more localized to its lateral third, giving {the} eyelid an S-shaped appearance. It may possibly extend further into {the} orbit, causing proptosis.
  • Diffuse orbital neurofibroma: The patient profile is similar to that of plexiform neurofibroma and usually presents with unilateral proptosis that may possibly or may possibly not involve {the} eyelids. It’s association with neurofibromatosis is not as strong as in plexiform neurofibroma.
  • Localized orbital neurofibroma: The typical patient is a young or middle-aged adult unlike {the} other forms which present in childhood. Clinical features include a solitary, well-circumscribed soft tissue tumour in {the} orbit causing proptosis and downward displacement of {the} globe. Less often, it can occur in {the} lacrimal gland and extraocular muscle, or even cause bony destruction to invade an adjacent sinus.

Diagnosis of Orbital Neurofibroma

  • Imaging studies are central to {the} evaluation of a suspected orbital neurofibroma. Both CT and MRI show smoothly marginated ovoid lesions, with or without lobulations.
  • Computerized Tomography: Shows lesions isodense or hypodense to extraocular muscles and shows variable contrast enhancement, with occasional ring-enhancement.
  • Magnetic Resonance Imaging: Demonstrates low-moderate T1 signal intensity and moderate-high T2 signal intensity. Heterogeneity of signal strength within {the} lesion is typical reflecting {the} mixed histopathology and vascularity of {the} tumours. Contrast enhancement is again variable.
  • Histopathology of a biopsy specimen or excised tumour confirms {the} diagnosis of orbital neurofibroma.

Treatment of Orbital Neurofibroma

  • The management of localized orbital neurofibroma consists of total excision, which is possible in about 46% of cases of isolated orbital neurofibroma. It also has {the} distinction of low recurrence after surgical excision. However, 72% of postoperative patients reported a sensory skin deficit.
  • However, {the} management of plexiform and diffuse orbital neurofibroma is complex, with an unpredictable outcome. Eyelid sparing orbital exenteration and orbital reconstruction is possibly {the} best treatment approach in patients with total eyelid ptosis and severe visual loss. Surgery is difficult due to diffuse infiltration and intracranial involvement. Recurrence after incomplete surgical removal is a common phenomenon. Hence, close follow-up is must.
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