Peer-reviewed veterinary case report
Benign peripheral nerve sheath tumor of the perianal region in a young pony.
- Journal:
- Journal of veterinary diagnostic investigation : official publication of the American Association of Veterinary Laboratory Diagnosticians, Inc
- Year:
- 2008
- Authors:
- Sturgeon, Ben P R et al.
- Affiliation:
- Royal (Dick) School of Veterinary Studies · United Kingdom
Plain-English summary
A 4-year-old Dales pony had a large, lobulated mass near its rear end that measured about 20 by 10 centimeters. Tests showed that the mass was a benign tumor made up of nerve sheath cells, which are related to the nerves in the area. Although the tumor looked harmless under the microscope, it grew deeply into the surrounding tissue, making it hard to remove completely during surgery. Because the entire tumor couldn't be taken out, it grew back after the surgery.
Abstract
A 20 x 10 cm, lobulated mass was present in the perianal region of a 4-year-old Dales pony. Histopathology revealed an unencapsulated, loose arrangement of sheets and whorls of narrow mesenchymal cells, situated in the deep dermis. Intervening areas had a myxomatous appearance. The whorls were often arranged around a central structure resembling an axon or a vascular structure. Immunohistochemistry revealed that the elongated mesenchymal cells and central axon-like structures expressed vimentin, S-100, and neuron-specific enolase, but not pancytokeratin, glial fibrillary acid protein, and the neurofilament markers, NR4 and 2F11. On the basis of the histopathology and immunohistochemistry, a diagnosis of benign peripheral nerve sheath tumor (schwannoma type) was made. This case was unusual in that the concentric laminations of Schwann cells were very loosely arranged, with an intervening myxomatous stroma (Antoni type B appearance) and despite its benign histological appearance, the mass extended deeply to the proximal sacral vertebrae. Its exact origin was unclear; it may have arisen from cutaneous nerves with deep extension or from neural structures in the sacral region. Due to the incomplete surgical removal, regrowth of the mass occurred.
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Search related cases →Original publication: https://pubmed.ncbi.nlm.nih.gov/18182519/