Neurofibromatosis type 1 is an autosomal-dominant hereditary disease of high penetrance and variable expression. The cardinal features of the disorder are café au lait spots, axillary freckles, multiple neurofibromas, and iris hamartomas (Lisch nodules). Intellectual handicap, scoliosis, and optic gliomas are also common, but peripheral nerve malignancy, bony deformities, and epilepsy are individually rare. 1–6 A case of a rare and unusual variant of neurofibroma, diffuse neurofibroma with intracranial extension, in a young patient is presented.
A 15-year-old girl was admitted to our clinic with a slow-growing, mobile, soft mass measuring 8 × 9 cm, which was located in the occipital region. Diffuse café au lait spots of various sizes (the diameter of 13 spots was greater than 1.5 cm) were present in different parts of her body, especially on the back, and she had freckles on her axillary areas. The patient was short, and she also had growth retardation compared with her age group. Ophthalmologic and neurologic examinations were normal. On the basis of these symptoms and findings, the diagnosis was neurofibromatosis type 1. (Fig. 1).
Cortical erosion under the lesion was seen on craniograms. The lesion was hypodense in noncontrast and hyperdense in contrast computed tomography scans. It extended intracranially from the occipitoparietal region in the midline, and it was noted to be very close to or actually invading the dura of the sagittal sinus. There was no intracranial shift (Fig. 2, above). On the basis of these findings and considering the fact that the lesion was located on the occipital scalp, the lesion was diagnosed as a diffuse neurofibroma, and angiography was performed preoperatively. No hemangiomatous vascular abnormalities were seen on the angiograms.
The operation was performed under mild hypotensive general anesthesia to cause minimal bleeding and, for this reason, a lazy-S incision was made on normal skin near the junction of the tumor.
After the elevation of the skin flaps, the mass was removed over the cranium. Cortical erosion was seen at the base of the mass, which required a wide craniectomy. Craniectomy revealed that the intracranial extension was very close to the dura of the sagittal sinus, and a small area showed tumor adherence. This area was resected, and a duraplasty was performed. The operation was completed after the subtotal resection of the tumor located at the occipital scalp and included total resection of its cranial extension.
The postoperative course was uneventful. The histopathological diagnosis was diffuse neurofibroma with areas of Meissnerian differentiation. The patient was healthy and symptom-free 38 months postoperatively. Postoperative control computed tomography scans performed at the end of the sixth and 15th months postoperatively showed no enlargement of the tumor mass (Fig. 2, below).
Diffuse neurofibroma principally occurs in children and young adults. Clinically, this tumor is most common in the head and neck region, and it presents as a plaque-like elevation of the skin. 1 Diffuse neurofibroma is an ill-defined tumor, and it spreads extensively along connective tissue septa and between the fat cells of the dermis and subcutaneous fat. Despite its infiltrative growth, it does not destroy, but rather envelops, the normal structures. It differs from conventional neurofibromas in that it has a very uniform matrix of fine fibrillary collagen. The sheets of the tumor may contain clusters of Meissner bodies, as in our patient. 1
This is an unusual variant of neurofibroma. Although benign, these tumors are prone to significant neovascularisation. For this reason, the vascularity of these tumors should be distinguished by angiography preoperatively; if necessary, a combination of preoperative intraarterial embolization should be performed. 1,7,8 Troublesome hemorrhage often occurs during the excision of the neurofibromatous tissue. Hypotensive anesthesia has proven to be effective in decreasing intraoperative bleeding. Because the vessels in tumor or skin lesions are abnormal, incisions must be made on normal skin if possible, which provides better bleeding control. 9,10
Diffuse neurofibromas are prone to erode through the skeletal structures and may have intracranial extension, which complicates surgical excision. Careful preoperative evaluation is essential. Bone deformities can be seen on plain films or computed tomography scans. Magnetic resonance imaging may be helpful in exceptional cases preoperatively to show where the extension close to the dura may be invading any of the sinuses. 1,2,7,11,12
Surgery is undertaken when the tumor is severely disfiguring or when function is seriously compromised, but complete removal is rarely achieved because of the extensive nature and multicentricity of the tumor. Serial excision is the generally accepted mode of treatment. Radical surgery is reserved for instances of malignant transformations. However, malignant transformation rarely occurs in the diffuse neurofibroma. 1,2,10,11
In conclusion, extracranially located diffuse neurofibromas may be extended intracranially. This issue must be addressed during the follow-up of these cases.
Selma Sönmez Ergün M.D.
Erhan Emel M.D.
I. Hüseyin Aydın M.D.
Selim Karabekir M.D.
Nesimi Büyükbabani M.D.
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