Plexiform neuroma
 

This patient has a left ptosis. The left upper is large and containsa subcutaneous mass (classically described as felt like a bag ofworms on palpation) which is immobile. (Note: in smaller plexiform neuroma, the ptotic eye may assume a S-shaped deformity). This is  plexiform neuroma and is associated with neurofibromatosis type I. Look for other signs of neurofibromatosis: there may be pulsatile exophthalmos due to absence of the greater wing of sphenoid bone. The pulsation results from transmittedcranial pulsation skin lesions such as cafe au lait spots on the back and axiallary freckles afferent pupillary defect or ptoptosis from optic nerve glioma on the slit-lamp look for Lisch's nodules and ectopia uvea and examine the disc for cupping (the incidence of glaucoma is high in patient with plexiform neuroma) and pallor (optic nerve glioma)

Questions:

1. How is type 1 neurofibromatosis transmitted?

answer
Autosomal dominant. The abnormal gene is located in chromososme 17q 11.2

2. What physical signs in type 1 neurofibromatosis is most strongly associated with glaucoma?

answer
plexiform neuroma and ectopia uvea.

3. What is the histology of plexiform neurofibroma?

answer
It is a peripheral nerve tumour made up of proliferating Schwann cells, endoneural fibrobalsts and axons.

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Lisch's nodules and a close-up view. Return to the top