King Edward Memorial Hospital - Departments: Radiology

Radiology

Case of the Month

Case No. :	29
Month :	May
Year :	2001
Contributor :	Dr. Diljeet Karayil

Other Cases

Case Report | Discussion

Case report:

A 17 year old boy presented with a swelling over the right side of his eye since 4 months of age. This swelling had gradually progressed to its present size. He has developed ptosis on that affected side. He also complained of swelling over the back and multiple "brownish white" areas over his chest, back and both the limbs. He did not have any history of convulsions or altered sensorium.

He performance at school was below average.

On his initial visits, radiographs of the skull were obtained. The frontal view is shown

Fig 1

Note the lateral displacement of the innominate line and the greater wing of the sphenoid as also the absence of the superior orbital fissure on the affected side. The characteristic anomaly of unilateral dysplasia of the wings of the sphenoid is called the "bare orbit". The rest of the skull appears normal. The differential diagnosis of this appearance any slow growing benign tumor within the orbit such as a hemangioma.

This is a classical example of neurofibromatosis type 2 or plexiform neurofibromatosis

The condition can be further verified with of MRI or CT scan.

Selected films of the MRI of the brain are shown. Note the classical herniation of the temporal lobe which is due to the lax , dysplatic dura overlying it.

Fig 2

Fig 3

Fig 4

Neurofibromatosis is a part of the generic classification of neurocutaneous syndromes. The neurocutaneous syndromes are also called as "phakamatoses" which in Greek stands for lentil or birth mark.

This heterogenous group of disorders has:

1. CNS manifestations

2. Cutaneous manifestations

3. Visceral and connective tissue abnormality

Neurofibromatosis is classified into into two main groups

1: Neurofibromatosis type 1/von Recklinghaunsens disease/peripheral neurofibromatosis

2: Neurofibromatosis type 2/bilateral acoustic schwanomas/central neurofibromatosis

Neurofibromatosis type 2 accounts for 90% of all the cases and is the most common "single gene congenital syndrome". It is observed in 1:2000 live births

Mutation is chiefly responsible for it and the gene is along the long arm of chromosome 17

Diagnostic criteria

When two or more of the given findings are present

1. More than 6 café au lait spots which are larger than 5 mm

2. Plexiform neurofibroma or two or more neurofibroma of any type

3. More than 2 pigmented nodules in the iris .they are also called as Lisch nodules

4. Axillary and inguinal region freckling

5. Optic nerve glioma

6. First degree relative with neurofibromatosis type 1

7. Bone lesions such as dyspalasia of the greater wing of sphenoid.

Lesions in neurofibromatosis may include the following

plexiform neurofibroma

Disfigurement.

NF1 can result in disfigurement in a number of ways. Skin neurofibromas may develop on the face or on the exposed areas of the arms or legs. The generally larger and deeper plexiform neurofibromas may grow around the eye or eyelid, or affect growth of one side of the face. Scoliosis of the spine (see below), can affect appearance when it is severe. Growths can occur around the nipple (periareolar neurofibromas) which may be distressing. Rarely, an overgrowth of skin or bone causes enlargement of an arm or leg.

In some people, the size or number of neurofibromas increase during puberty and pregnancy, reflecting a possible hormonal effect.

Scoliosis.

Lateral curvature of the spine, known as scoliosis, is common in NF1. In most cases it is mild. Scoliosis usually appears in early childhood.

Large Heads.

Children and adults with NF1 often have large head circumference, which usually does not indicate any significant medical problem. Very rarely, large head circumference results from hydrocephalus, a serious problem which may require surgery. Imaging of the brain with CT scan or MRI can help determine if head enlargement is serious or not. Head circumference in children with NF1 should be measured periodically.

Optic Gliomas.

An optic glioma is a tumor of the optic nerve (the nerve which controls vision). This tumor, which fortunately is uncommon, usually appears in childhood and is first noticed because of poor or failing vision or bulging of the eye. Children with NF1 should have routine eye examinations by an ophthalmologist, neurologist or physician familiar with this problem. Treatment for this condition includes surgery and radiation therapy.

Congenital Defects of Bone.

The variety of bone defects seen in NF1 are usually evident at birth. Most are uncommon. Defects can occur in almost any bone, but are seen most often in the skull and limbs. They include:

Congenital absence of the orbital wall. Its absence may cause slight bulging of the skin around the eye.
Bowing of the leg bones below the knee (tibia or fibula). These bones may be thinner than normal and bowed. If a fracture occurs, healing may be slow or incomplete. Incomplete healing, called pseudarthrosis, may also affect the bones in the forearm (radius or ulna), but this occurs very rarely.

Hypertension

People with NF1 can have hypertension for reasons completely unrelated to NF1. However, two rare problems associated with NF1 may result in hypertension: renal artery stenosis and pheochromocytoma, a rare and usually benign tumor of the adrenal gland. Both of these problems are treatable. Because of these possible problems, it is important that routine physical exams for children and adults with NF1 include blood pressure checks.