Intratumoral collagen index predicts mortality and survival in canine cutaneous mast cell tumours

Background Mast cell tumours (MCTs) constitute almost 25% of cutaneous neoplasms in dogs. Their biological behaviour is predicted using histopathological grading which is based on several subjective criteria that are vulnerable to intra‐ and interobserver variability. To improve the prediction of the biological behaviour, several complementary markers have been studied. The integrity of the extracellular matrix (ECM) may play a protective role against tumoral progression, and favour cellular proliferation, angiogenesis, invasion and metastases when altered. Hypothesis/Objectives To evaluate the quantification of collagen and elastic fibres as prognostic markers for MCTs. Animals Thirty‐eight random cases of canine cutaneous MCT surgically treated with wide margins were included. Methods and materials Intratumoral collagen and elastic fibres were identified and quantified on histological sections stained with Masson's trichrome, Picrosirius red and Verhoeff; the results were compared with histopathological grades, mortality due to the disease and postsurgical survival. Results Morphometric analysis revealed a significant relationship between histopathological grade and intratumoral collagen index (CoI). In addition, the CoI was considered an independent indicator for mortality and postsurgical survival. Conclusions and clinical importance These results support the importance of the CoI in the grading and prognosis of MCTs, suggesting that preservation and/or synthesis of collagen have the potential to become targets for MCT therapeutics. Résumé Contexte Les mastocytomes (MCTs) représentent presque 25% des tumeurs cutanées du chien. Leur évolution biologique est prédictible par gévaluation histopathologique basée sur plusieurs critères subjectifs qui sont vulnérables d'un point de vue variabilité intra et inter‐observateur. Pour améliorer la prédiction de l’évolution biologique, plusieurs marqueurs complémentaires ont été étudiés. L'intégrité de la matrice extracellulaire (ECM) pourrait jouer un rôle protecteur contre la progression tumorale et son altération pourrait favoriser la prolifération cellulaire, l'angiogenèse, l'invasion et les métastases. Hypothèses/Objectifs Evaluer la quantification des fibres de collagène et des fibres élastiques comme facteurs pronostics des MCTs. Sujets Trente huit cas de MCT canins traités par chirurgie avec de larges marges ont été inclus. Matériel et méthode Le fibres élastiques et de collagène intra‐tumorales ont été ide