Evaluating the Histologic Grade of Digital Squamous Cell Carcinomas in Dogs with Dark and Light Haircoat—A Comparative Study of the Invasive Front and Tumor Cell Budding Systems

Abstract

Canine digital squamous cell carcinomas (CDSCC) are particularly aggressive when compared to their occurrence in other locations. Although these neoplasms are more frequently seen in dark-haired dogs, such as Giant Schnauzers, there are no data checking whether these tumors are histologically different between breeds. We histologically evaluated DSCC from 94 dogs. These were divided into two groups, namely, (1) dark-haired (N = 76) and (2) light-haired breeds (N = 18), further subdividing Group 1 into three subgroups, (1a) black breeds (n = 11), (1b) Schnauzers (n = 34) and (1c) black & tan breeds (n = 31). Adaptations from two different squamous cell carcinomas grading schemes from human and veterinary literature were used. Both systems showed significant differences when compared to Groups 1 and 2 in terms of final grade, invasive front keratinization, degree of invasion, nuclear pleomorphism, tumor cell budding, smallest tumor nest size and amount of tumor stroma. Group 2 was consistently better differentiated CDSCC than Group 1. However, there were no significant differences among the dark-haired breeds in any of the features evaluated. This study represents the first attempt to grade CDSCC while taking into account both phenotypical and presumptive genotypical haircoat color. In conclusion, CDSCC are not only more common in dark-haired dogs, they are also histologically more aggressive.

Clinical Features and Outcome of 79 Dogs With Digital Squamous Cell Carcinoma Undergoing Treatment: A SIONCOV Observational Study

“…In the current retrospective multicenter study, 79 dogs with digital SCC were included. Based on our findings, we confirm that dark-coated dogs were over-represented similarly to earlier findings, with Schnauzers representing approximately one third of the population, further implicating a possible familial association and/ or genetic pre-disposition as previously described (12,16,17). Additionally, according to the univariate analysis, the Schnauzer breed was linked to a higher risk of tumor-specific death compared with all other breeds.…”

Digital Lesions in Dogs: A Statistical Breed Analysis of 2912 Cases

“…Hypothetically, if this copy number variation is also responsible for other predisposed breeds (e.g., Schnauzer) this must be investigated in further studies. Additionally, a previous study demonstrated that the digital SCC of dark-haired breeds had more histologically malignant features than their light-haired counterparts [ 26 ]. Nevertheless, this represents the first study identifying Jack Russell Terriers to have a significantly lower risk of developing digital SCC.…”

KITLG Copy Number Germline Variations in Schnauzer Breeds and Their Relevance in Digital Squamous Cell Carcinoma in Black Giant Schnauzers

“…Amputation of the toe is the treatment of choice in dogs with dSCC [ 10 ]. The histological grade of malignancy can be assigned by two different systems adapted from human squamous cell carcinomas [ 11 , 12 ] to canine digital squamous cell carcinomas [ 13 ]. The risk of local recurrence can be considered low when resected in healthy tissue.…”

“…Dark coat colour is correlated to the development and aggressiveness of squamous cell carcinoma [ 1 , 2 , 3 , 4 , 5 , 6 , 13 , 16 ]. A predisposition for squamous cell carcinoma in standard schnauzers (SS) and giant schnauzers (GS) has been identified by various authors [ 1 , 4 , 5 , 6 , 17 ].…”