Peer-reviewed veterinary case report
Pony has a lump near the rear - what could it be?
By Sturgeon, Ben P R et al.·Published in Journal of veterinary diagnostic investigation : official publication of the American Association of Veterinary Laboratory Diagnosticians, Inc·2008·Royal (Dick) School of Veterinary Studies, United Kingdom·View original on PubMed →
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Original publication title: Benign peripheral nerve sheath tumor of the perianal region in a young pony.
- Species:
- horse
Plain-English summary
A 4-year-old Dales pony had a large, lobulated mass near its rear end that was found to be a benign peripheral nerve sheath tumor, which is a type of growth related to nerve tissue. The tumor was diagnosed after examining tissue samples, and it was noted that it extended deeply toward the pony's spine. Unfortunately, the mass could not be completely removed during surgery, leading to regrowth. This case highlights the importance of careful monitoring and follow-up treatment for similar tumors in pets.
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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 on PubMed: https://pubmed.ncbi.nlm.nih.gov/18182519/