Equine Melanocytic Tumors: A Narrative Review.
Authors: Pimenta José, Prada Justina, Cotovio Mário
Journal: Animals : an open access journal from MDPI
Summary
# Equine Melanocytic Tumours: Clinical and Genetic Insights Grey horses face substantially elevated risk of developing melanocytic tumours, a challenge that has prompted renewed investigation into the genetic and molecular mechanisms underpinning these lesions. This 2023 narrative review synthesises current understanding of key genetic mutations—particularly STX17, ASIP, and MITF alterations—alongside the well-documented association between the greying process and melanoma formation, providing a comprehensive framework for clinicians managing affected animals. The authors establish a clear pathological classification system distinguishing naevus, dermal melanoma, dermal melanomatosis, and anaplastic malignant melanoma, whilst identifying fine-needle aspiration and histopathology as the most reliable diagnostic approaches, with emerging biomarkers (RACK1 and PNL2) showing promise via immunohistochemistry. Current therapeutic options—surgery, chemotherapy, and electroporation—are outlined alongside novel treatment targets including CD47, PD-1, and COX-2 inhibition, which reflect developing immunological and anti-inflammatory strategies. For equine practitioners, this review underscores the importance of early identification and classification in tailoring treatment strategy, whilst highlighting that immunotherapeutic approaches may offer future alternatives to conventional modalities, particularly for advanced or multifocal disease.
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Practical Takeaways
- •Grey horses require increased vigilance for melanocytic tumors; establish baseline clinical assessment and regular monitoring protocols for at-risk animals
- •Histopathology with immunohistochemistry provides definitive diagnosis and guides treatment selection; fine needle aspiration offers quick preliminary assessment
- •Multiple therapeutic options exist beyond surgery alone; chemotherapy and electroporation may be considered based on tumor classification and clinical presentation
Key Findings
- •Adult grey horses have high incidence of melanocytic tumors with genetic features including STX17 mutation, ASIP and MITF alterations linked to graying process
- •Fine needle aspiration and histopathology are most relevant diagnostic methods, with immunohistochemistry biomarkers RACK1 and PNL2 providing important diagnostic value
- •Therapeutic options include surgery, chemotherapy, and electroporation as most common treatments
- •Emerging research targets include CD47, PD-1, and COX-2 biomarkers as novel therapeutic approaches