Thoracic and Abdominal Mesothelioma in an Older Horse in Lazio Region.
Authors: Passantino Giuseppe, Sassi Emilio, Filippi Ilaria, Serata Valerio, Tinelli Antonella, Zizzo Nicola
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary A 22-year-old Quarter Horse gelding presented with clinical signs of colic, prompting investigation that revealed massive pleural (50 litres) and peritoneal (100 litres) effusions alongside abdominal masses on ultrasonography. Cytological examination of the aspirated fluids, combined with post-mortem histopathology and immunohistochemistry (positive for cytokeratin and vimentin), confirmed a diagnosis of epithelioid mesothelioma affecting the peritoneum, omentum, mediastinum, lungs, and heart. Whilst mesothelioma remains exceptionally rare in equine geriatric cases, this report underscores the importance of including mesothelial malignancy in differential diagnoses when older horses present with unexplained polyserositis and significant fluid accumulation refractory to standard investigation. The authors highlight the value of advanced diagnostic imaging, fluid analysis, and histological confirmation in establishing definitive diagnoses ante-mortem, which may guide palliative management decisions and inform prognostication—particularly relevant given that environmental factors may influence disease incidence at a population level.
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Practical Takeaways
- •Consider mesothelioma in differential diagnosis for older horses presenting with massive pleural and abdominal effusions and unexplained colic; use immunohistochemistry (CK and vimentin positivity) for confirmation
- •Cytology of body cavity fluids combined with imaging can support ante-mortem diagnosis before euthanasia; this improves clinical decision-making and documentation
- •Monitor equine populations in your region for mesothelioma cases as horses may serve as sentinel animals for environmental asbestos contamination affecting both animal and human health
Key Findings
- •A 22-year-old Quarter Horse gelding presented with mesothelioma manifesting as 50 L pleural effusion and 100 L abdominal effusion with nodular masses
- •Epithelioid mesothelioma was confirmed via histopathology and immunohistochemistry with positive cytokeratin and vimentin antibodies
- •Mesothelioma is rare in older horses and requires appropriate differential diagnostics to support ante-mortem clinical diagnosis
- •Use of equine cases as biological indicators for territorial asbestos exposure monitoring is recommended