Page 909 - Textbook of Pathology, 6th Edition

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Figure 30.20 Schwannoma (neurilemmoma), showing whorls of densely cellular (Antoni A) and loosely cellular (Antoni B) areas with characteristic
nuclear palisading (Verocay bodies).

Mononeuropathy multiplex or multifocal neuropathy Microscopically, the tumour is composed of fibrocellular
is defined as simultaneous or sequential multifocal bundles forming whorled pattern. There are areas of dense
involvement of nerve trunks which are not in continuity. The and compact cellularity (Antoni A pattern) alternating with
involvement may be partial or complete and may evolve over loose acellular areas (Antoni B pattern). Areas of Antoni A
days or years. Multifocal neuropathy represents part of pattern show palisaded nuclei called Verocay bodies CHAPTER 30
spectrum of chronic acquired demyelinating neuropathy. (Fig. 30.20). Nerve fibres are usually found stretched over

Mononeuropathy, on the other hand, is focal involve- the capsule but not within the tumour. Areas of
ment of a single nerve. It is generally the result of local causes degeneration contain haemosiderin and lipid-laden
such as direct trauma, compression and entrapment. macrophages. Schwann cells characteristically express
S-100 protein. A schwannoma rarely ever becomes
NERVE SHEATH TUMOURS malignant.
Tumours of the peripheral nerves are commonly benign and
include schwannoma (neurilemmoma) and neurofibroma. Neurofibromas and von Recklinghausen’s Disease
Both of them arise from Schwann cells but neurofibroma Neurofibromas may occur as solitary, fusiform cutaneous The Nervous System
contains large amount of collagen. Rarely, their malignant tumour of a single nerve, but more often are multiple
counterpart, malignant peripheral nerve sheath tumour, associated with von Recklinghausen’s disease. Solitary
develops particularly in patients with von Recklinghausen’s neurofibroma is a tumour of adults but multiple
neurofibromatosis. neurofibromas or neurofibromatosis is a hereditary disorder
with autosomal dominant inheritance. Solitary neurofibroma
Schwannomas (Neurilemmomas) is generally asymptomatic but patients with von
Schwannomas or neurilemmomas arise from cranial and Recklinghausen’s disease have a triad of features:
spinal nerve roots. An acoustic schwannoma or acoustic neuroma Multiple cutaneous neurofibromas.
is an intracranial schwannoma located within the internal Numerous pigmented skin lesions (‘cafe au lait’ spots).
auditory canal originating from vestibular portion of the Pigmented iris hamartomas.
acoustic nerve (page 515). Intraspinal schwannomas are found Neurofibromatosis type 1 is a genetic disorder having
as intradural tumours in the thoracic region. In the peripheral mutation in chromosome 17 while type 2 has mutation in
nerves, they occur as solitary nodule on any sheathed chromosome 22.
sensory, motor, or autonomic nerve. Multiple schwannomas
are uncommon and occur in von Recklinghausen’s disease MORPHOLOGIC FEATURES. Grossly, neurofibroma is
(see below). Schwannomas are tumours of adults except in an unencapsulated tumour producing fusiform enlarge-
von Recklinghausen’s disease.
ment of the affected nerve. Neurofibromatosis in von
MORPHOLOGIC FEATURES. Grossly, a schwannoma Recklinghausen’s disease is characterised by numerous
is an encapsulated, solid, sometimes cystic, tumour that nodules of varying size, seen along the small cutaneous
produces eccentric enlargement of the nerve root from nerves but may also be found in visceral branches of
where it arises. sympathetic nerves. Neurofibromatosis may involve a