Peer-reviewed veterinary case report
Congenital myofibroblastic fibrosarcoma of the temporal bone in a newborn Arabian foal.
- Journal:
- Journal of comparative pathology
- Year:
- 2025
- Authors:
- Johnson, Jessica P et al.
- Affiliation:
- Abu Dhabi Equine & Camel Hospital
- Species:
- horse
Plain-English summary
A newborn Arabian foal was found to have a rare type of cancer called congenital myofibroblastic fibrosarcoma (MFS), which is a malignant soft tissue tumor. The foal had a large mass under the skin on the left side of its head, near the temporal bone. This mass was soft, white-yellowish, and attached to the bone, and tests showed it was made up of abnormal cells that were invading nearby tissues but had not spread to other parts of the body. The diagnosis was confirmed through detailed examination of the mass's structure and specific tests on the cells. This case is notable because it is the first documented instance of this type of cancer occurring in animals.
Abstract
Myofibroblastic fibrosarcoma (MFS) is a malignant soft tissue tumour that is rare in domestic animals. Here we report a case of congenital MFS in an Arabian foal at birth. A large solitary subcutaneous mass arising in the left temporal region was found in the foal. On cut section, an unencapsulated hemispheric, white-yellowish, elastic fibrous mass was attached to the temporal bone. Histologically, the mass was composed of a neoplastic proliferation of spindle-shaped fibroblasts arranged in fasciculate or interwoven streams and bundles, with low nuclear atypia and mitotic rate, local invasion of the surrounding soft tissues and temporal bone, non-metastasis and abundant collagenous stroma. Immunohistochemically, vimentin, calponin, desmin and alpha-smooth muscle actin were strongly and diffusely labelled, S100 was mildly labelled and h-caldesmon was weakly labelled in the cytoplasm of the neoplastic cells; however, the neoplastic cells were immunonegative for pancytokeratin AE1/AE3 and p63. Based on the histological and immunohistochemical findings, a diagnosis of MFS was made. To our knowledge, this is the first report of congenital MFS in animals.
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Search related cases →Original publication: https://pubmed.ncbi.nlm.nih.gov/39923733/