Endocardial Peripheral Nerve Sheath Tumour with Features of a Benign Schwannoma in a Donkey.

This research paper discusses a rare case of benign schwannoma, a nerve sheath tumour, originating from the right ventricle of the heart in a 28-year-old gelding donkey – the first cardiac tumour incident in donkeys reported. This type of tumour, revealed during a routine post-mortem examination, has shown similarities to endocardial schwannoma observed in Wistar rats, in terms of its macroscopic, histological, and immunohistological presentation.

Overview of the Study

• The research was instigated after the identification of a benign schwannoma, a type of peripheral nerve sheath tumour, in a donkey – an exception to the typical instances of such tumours.
• The study mentions that the tumour was discovered unexpectedly – during a standard post-mortem examination of the donkey, aged 28 years.
• The primary point of interest for the researchers is the location of the tumour – it originated from the endocardium of the right ventricle in the donkey’s heart, a previously unreported occurrence.

Findings and Analysis

• The tumour consisted of five round to oval, firm, white to grey and red masses securely attached to the endocardium.
• Upon microscopic analysis, the researchers discovered that the endocardium and its adjacent subendocardium were invaded by a mesenchymal neoplasm that was variably demarcated and non-encapsulated.
• Several characteristic features of benign schwannoma were observed, such as the presence of Antoni A and Antoni B areas, nuclear palisading, neoplastic cells with unusually enlarged nuclei or ‘ancient change’, and the creation of Verocay-like bodies. These features provided a significant cue for diagnosing the tumour.
• Immunohistochemically, the tumour cells exhibited variable but strong positivity for the expression of S100 and glial fibrillary acidic protein, complementing the pathological data obtained.

Significance and Conclusion

• This case is considered unique due to its location in the heart and the host species being a donkey—both previously unreported scenarios.
• It adds significant knowledge to the field of veterinary oncology, particularly regarding peripheral nerve sheath tumours in non-typical locations or species.
• Moreover, the resemblance of this cardiac tumour to the endocardial schwannoma observed in Wistar rats indicates possible similar disease processes in different species, providing a valuable perspective for comparative oncology.