The Characteristics of 924 Cutaneous Mast Cell Tumours in Dogs ≤ 3 Years of Age—With a Short Literature Review of Feline, Equine, and Human Proliferative Mast Cell Disorders
Source: PubMed Central Open Access, NCBI / U.S. National Library of Medicine
Simple Summary Mast cell tumours are the most common round cell tumours in the skin of dogs. In young dogs, benign histiocytomas occur very frequently, but potentially malignant mast cell tumours are an important differential diagnosis. Our study aimed to characterise the cutaneous mast cell tumours in dogs ≤ 3 years in more detail to improve clinical and diagnostic differentiation. The study retrospectively analysed 924 mast cell tumours submitted from 849 dogs for routine diagnostics between 2014 and 2023. Our data suggest that most breeds with a well-known breed predisposition to cutaneous mast cell tumours have a high risk at a young age. Overall, the proportion of high-grade mast cell tumours was lower compared to older dog populations. However, significant breed-related differences in the prevalence of high-grade tumours were identified: Boxers and Pugs developed low-grade mast cell tumours more often than crossbreeds, and tumours on the ear were more often low grade. Mast cell tumours developed in similar locations to those reported in adult dogs, most commonly involving the trunk. Pugs and Golden Retrievers more frequently showed multiple mast cell tumours simultaneously. Our findings warrant heightened vigilance in evaluating cutaneous lesions in young dogs and highlight similarities and differences compared with the general dog population. plain-language-summary Abstract Datasets from 849 dogs ≤ 3 years of age were analysed retrospectively, considering breed, sex, a
Abstract
Simple Summary Mast cell tumours are the most common round cell tumours in the skin of dogs. In young dogs, benign histiocytomas occur very frequently, but potentially malignant mast cell tumours are an important differential diagnosis. Our study aimed to characterise the cutaneous mast cell tumours in dogs ≤ 3 years in more detail to improve clinical and diagnostic differentiation. The study retrospectively analysed 924 mast cell tumours submitted from 849 dogs for routine diagnostics between 2014 and 2023. Our data suggest that most breeds with a well-known breed predisposition to cutaneous mast cell tumours have a high risk at a young age. Overall, the proportion of high-grade mast cell tumours was lower compared to older dog populations. However, significant breed-related differences in the prevalence of high-grade tumours were identified: Boxers and Pugs developed low-grade mast cell tumours more often than crossbreeds, and tumours on the ear were more often low grade. Mast cell tumours developed in similar locations to those reported in adult dogs, most commonly involving the trunk. Pugs and Golden Retrievers more frequently showed multiple mast cell tumours simultaneously. Our findings warrant heightened vigilance in evaluating cutaneous lesions in young dogs and highlight similarities and differences compared with the general dog population. plain-language-summary Abstract Datasets from 849 dogs ≤ 3 years of age were analysed retrospectively, considering breed, sex, anatomic sites, multiplicity, tumour diameter, grading, and immunohistochemistry by using IBMSPSS Statistics (version 29.0.2.0). Danish–Swedish farm dogs (OR: 8.11, 95% CI 3.33–19.77,< 0.001) and English Setters (OR: 6.68, 95% CI 3.20–13.97,< 0.001) showed the highest odds ratios (ORs) compared to crossbreeds. German Shepherd Dogs showed lower ORs (OR: 0.05, 95% CI 0.007–0.364,< 0.01). The most common sites affected in the young dogs were the trunk (39.2%), hind limbs (24.9%), head (10.1%), fore limbs (7.4%), and pinnae (5%). Patnaik grading revealed 330 grade I (35.7%), 580 grade II (62.8%), and 14 grade III MCTs (1.5%). Kiupel “low grade” was found in 903 MCTs (97%), and 21 MCTs were “high grade” (3%). The prevalence of grade I MCTs was higher in Boxers (48.0%,< 0.05) and Pugs (67.9%,< 0.01). Pinnal MCTs were mostly grade I (58.3%,< 0.01). In 6% (= 51), multilocalised MCTs were found, and Golden Retrievers (12.5%,= 0.02) and Pugs (21.4%,= 0.005) were more affected than crossbreeds. Out of 87 dogs, 20 showed a Ki-67 count above the cut-off as well as KIT staining pattern II. The findings warrant heightened vigilance in evaluating cutaneous lesions in young dogs and highlight similarities and differences compared to the general dog population. Analysis of survival data is required to evaluate how the findings translate into a clinical setting.