Epidemiological Aspects and Differential Diagnosis of the Cutaneous Round Cell Tumors in Dogs

Abstract

Round cell neoplasms (RCNs) are frequent cutaneous lesions in dogs, with high percentages among skin tumors. In this category are included histiocytoma, mast cell tumor, plasmacytoma, lymphoma and transmissible venereal tumor. The aim of the study was to perform an epidemiological study with reference to the cutaneous round cell tumors in a period of 10 years in the Department of Pathology (Faculty of Veterinary Medicine, ClujNapoca, Romania). Additionally, in the recorded cases with round cell tumors (mast cell tumor, histiocytoma and lymphoma) we described the main histological and cytological features. The epidemiological data were collected from the records of Pathology Department between 2005-2014. The investigation included dogs diagnosed with cutaneous round cell neoplasms, following necropsy analysis or assessment of biopsies or cytological samples. All collected specimens were analyzed by histopathological and/or cytological techniques. The staining used for histological investigation were Hematoxylin-eosin, Masson's trichrome and Toluidine blue, whereas Diff Quikand Wright methods were utilized in cytological specimens. The distribution of the cutaneous round cell tumors in relation to age, breed and sex was also assessed. The most frequent round cell tumor type was the mast cell tumor (19.54%) followed by histiocytoma (11.33%) and lymphoma (1.98%). The round cell tumors recorded were equally distributed in both males and females. Concerning the distribution of cutaneous RCNs by age (average age), histiocytoma occurred in 5 years old subjects, mast cell tumor in 11.9 years old subjects, and lymphoma in 6 years old subjects. Mast cell tumor was more frequent in stray dogs and Boxer breed, while histiocytoma occurred more commonly in stray dogs. Histological and cytological analysis was mandatory to perform the differential diagnosis between RCNs. Microscopic details concerning cytoplasm and nucleus of tumoral cells, together with the displaying mode in histological specimens may reveal the type of RCN. Cutaneous round cell tumors had an increased incidence, aspect observed in other reports too. The differential diagnosis has to rely on some specific microscopical features that can suggest the type of RCN.

Epidemiology of canine cutaneous round cell tumours on the canary archipelago in Spain

“…Concerning age at diagnosis, in our study, MCT were diagnosed on an average age of 8.38 years old which is consistent with former studies 6,16,18,23,26,27,[29][30][31] although one study found average age being older (around 11 years old). 15 Also, our results analysing differences in age depending on the grade of MCT were similarly consistent with other studies 23,29 in that the proportion of high grade MCT increases with advancing age. In this regard, the previously described aging of the canine population in our region could explain, at least partially, why we obtained smaller proportion of grade 1 MCT (3.4%) and higher ones of grade 2 MCT (86.5%), when compared with previous works 6,14,19,23,30,34 that obtained results ranging from 12.9% to 33.3% for grade 1 and from 33.6% and 76.3% for grade 2.…”

“…We found male dogs to be at a greater risk of HCT which is adds to the discordance in the literature about the relevance of sex to this tumour type. 15,41 Our results for sex as a factor risk for PLA revealed no differences in risk due to sex for this tumour type, although the only reference to compare with found a greater proportion of males versus female dogs in a sample of 49 dogs suffering from PLA. 36,37 Finally, when comparing the results obtained in different islands, we saw a lower risk in all islands when compared with Gran Canaria although this is mostly due to an overrepresentation of cases submitted from Gran Canaria to the APDS as explained below.…”

“…Former studies had mostly found no differences in this regard 15,19,26,27,30,33 while others found higher risk for females. 29 Regarding breed and risk of HCT, we also found Bulldog-related breeds mentioned previously for MCT and Retrievers plus the addition of West Highland White Terrier (third breed with greater risk), as well as the Cocker, German Pinscher and Beagle to be at greater risk of developing HCT.…”

“…venereal tumour, histiocytic sarcoma melanoma and neuroendocrine tumours. 11 Previous studies conducted on several countries such as the United States, 12,13 Denmark, 14 Romania, 15 Switzerland, 16 Portugal, 17 Korea 18 and Japan 19 have described the epidemiology of several canine skin tumours including MCT and, to a lesser extent, HCT and PLA. Additionally, other studies in the United States, [20][21][22][23] the United Kingdom, [24][25][26] Italy, 27 Poland, 28,29 Portugal, 30 Austria, 31 Croatia 32 and Australia 33,34 have focused specifically on different aspects of MCT epidemiology such as the association of breeds, age or anatomical distribution and the presence of simultaneous MCT.…”

Prevalence and distribution of canine neoplastic and non-neoplastic cutaneous lesions in Serbia: a retrospective study of 2432 Cases (2011 – Mid 2021)

“…The expression of CD117 in cytoplasm was observed in 64.29% of high-grade malignancy mast cell tumors, while mutations of c-KIT proto-oncogene were not found in tumor samples from dogs with mast cell tumor [24,25]. Roundcell tumors are among the most common cutaneous tumors, and the established distribution of mast cell tumor, histiocytoma and lymphoma are close to the results presented by other authors [26].…”