Schwannoma pathology

Author: Assoc Prof Patrick Emanuel, Dermatopathologist, Auckland, New Zealand, 2013.

Schwannoma is also known as an “neurilemmoma”, “neurolemmoma”, and “Schwann cell tumour”. It is a benign peripheral nerve sheath tumour composed of Schwann cells. Schwann cells normally produce the insulating myelin sheath covering peripheral nerves.

Histology of schwannoma

In schwannoma, sections show an encapsulated well-circumscribed lesion beneath the uninterrupted epidermis. The tumour is composed of different areas composed of different cellular densities. More cellular areas (Antoni A, figure 1) are composed of a haphazard arrangement of bland cells with spindled and oval nuclei. Loose, less cellular areas (Antoni B, figure 2) are composed of a loose oedematous and mucinous stroma with fibrillar collagen. The vessels are prominent and often surrounded by a dense sclerosis.

Characteristic Verocay bodies may be seen (figure 3). These consist of parallel columns of elongated nuclei on either side of a homogeneous acellular material.

An associated peripheral nerve can usually be seen.

Occasionally, “ancient change” or cellular atypia believed to be a reactive phenomenon may be seen (figure 4).

Special studies for schwannoma

Schwannomas are strongly positive with S100.

Differential diagnosis of schwannoma pathology

Neurofibroma – Lacks the Antoni A and B pattern of schwannoma and is not encapulated. Plexiform neurofibroma may resemble schwannoma. Neurofibromas typically have nerves coursing through the mass which can be demonstrated with immunohistochemical staining with neurofilament.

Perineurioma – These are EMA positive and S100 negative.

Dermatofibromasarcoma protuberans – These are positive with CD34, lack S100 positivity and lacks the Antoni A and B pattern of schwannoma. Additionally, they are not encapulated.

Related information

Make a donation

Donate Today

Help us to update and maintain DermNet New Zealand

The History Of DermNet

Watch Dr Amanda Oakley presenting 'The History Of DermNet NZ' at The International Society Of Teledermatology.

Subscribe to our mailing list

* indicates required
DermNet NZ Newsletter