Large retrospective study identifies common skin masses in young dogs

27 January 2022

A study published in the latest issue of the Journal of Small Animal Practice (JSAP) found that the most common skin masses in dogs aged between 0 and 12 months were histiocytoma, papilloma, dermoid cyst, follicular cyst and mast cell tumours (MCTs).

In the study titled “Skin masses in dogs under 1 year of age: 2554 cases (2006-2013)&”, records from a large commercial diagnostic laboratory were searched for canine skin masses submitted for histopathology from dogs aged between 0-12 months from practices based in the UK and Europe. For each case, data on the breed, age and sex of the dog, the body location of the sample, and the diagnosis made by the original reporting histopathologist were recorded. For the purposes of the study, masses were included which were cystic, hyperplastic or neoplastic, but not inflammatory. Submissions of samples from the eyes, anal glands and nails were excluded. Only MCTs submissions that were cutaneous were included. Risk factor analysis using multivariable binary logistic regression modelling was carried out for skin masses with at least 30 submissions.

Professor Ken Smith, corresponding author for the paper, said: “A total of 2553 submissions for a skin mass were included in the study. Across all the skin masses, the majority (94.3%) were neoplastic in nature. Of the neoplastic lesions, 98.5% were considered benign. Almost all of the benign neoplastic lesions were of round cell origin (94.0%), whereas most of the non-neoplastic lesions were derived from the epithelium (93.8%).

“The most common histopathological diagnoses for skin masses were histiocytoma (86.6%), papilloma (3.5%), dermoid cyst (3.3%), follicular cyst (1.7%) and MCT (1.4%). Multivariable analysis revealed that Labrador retrievers, Boxers and Golden retrievers had reduced odds of histiocytoma compared to crossbreed dogs. Male neutered dogs had lower odds of dermoid cyst compared with female entire animals. Dogs aged 9 to 12 months had significantly higher odds of follicular cyst compared with dogs aged under 6 months, whilst dogs aged over 6 months showed significantly higher odds of MCT than dogs under 6 months of age.&”

Nicola Di Girolamo, Editor of JSAP, concluded: “Retrospective studies that include a large number of cases such as this one are an invaluable resource for clinicians working in any setting. The findings of this study corroborate those of previous research, suggesting that a skin mass in a young dog is very likely to be a histiocytoma. However, the risk factor analysis in this paper identified a number of different predilections to those previously recognised, indicating a need for continued research in this area.&”

The full article can be found in the January issue of the Journal of Small Animal Practice and can be read online here:

The Journal of Small Animal Practice is published monthly and access to articles is free for BSAVA members.

1Kim D, Dobromylskyj MJ, O’Neill D and Smith KC (2022) Skin masses in dogs under 1 year of age: 2554 cases (2006-2013). Journal of Small Animal Practice, 63 (1). Available at: