Tumour-associated macrophages (TAMs) are an important part of the tumour microenvironment but knowledge of their distribution in canine soft tissue sarcomas (STSs) is limited to absent. We analysed 38 STSs retrieved from the veterinary pathology archive; oral and visceral STSs, synovial cell sarcoma, tumours of histiocytic origin, haemangiosarcoma, carcinosarcomas, and undifferentiated tumours were excluded. Iba-1 positive, non-neoplastic tumour infiltrating cells (morphologically indicative of macrophages) were classified as TAMs and were counted in 10 consecutive tumours areas, where no necrosis or other inflammatory cells could be identified. Associations between numbers of TAMs and mitoses, differentiation, and necrosis scores or grade were investigated. TAMs were evident in all STSs and ranged between 6% to 62% of the cells in the microscopic field. The number of TAMs positively correlated with the STSs’ histologic grade. When the components of the grade were analysed separately, TAMs were statistically correlated with mitoses, but not with differentiation or necrosis score. The present findings suggest that TAMs are present in higher numbers when STS proliferation is the predominant feature that drives tumour grade. The abundant presence of TAMs in high-grade STSs may also increase the likelihood of a pathologist misdiagnosing STS for histiocytic sarcoma.

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While Brunner's gland hyperplasia may rarely be considered as a cause of chronic gastric impaction in horses, it should be included in the differential diagnoses. A 7‐year‐old Cob cross‐breed gelding was presented with weight loss over a 3‐week period, and a diagnosis of chronic gastric impaction was made. Initial medical management was successful; however, the impaction recurred a further three times, at progressively shorter intervals, over the following 3 months. The owners subsequently elected euthanasia, and the horse was submitted for post‐mortem examination. A focal nodule within the cranial part of the duodenum was seen during the post‐mortem exam. Histopathologic evaluation of the duodenum revealed a marked increase in Brunner's glands admixed with distinct lobules of exocrine pancreatic tissue.

Biopsies from 92 dogs with TCC were routinely processed for histopathology and graded into low grade or high grade, according to Meuten & Meuten (2017). DNAisolation from paraffin embedded material was performed with the use of commercially available sets. Exon 15 was examined for the presence of the BRAF variant c.1784T > A by TaqMan ® SNP Assay. RESULTS 64/92 TCCs were classified as high grade and 28/92 as low grade. BRAF mutation was found in 33/64 (51.5%) of the high grade and in 12/28 (42.8%) of low grade TCCs. STATEMENT (CONCLUSIONS) BRAF variant analysis is a new, highly specific diagnostic test for TCC. However, it is important to note that only identification of the mutation is diagnostic. It must be taken into consideration that histologically low grade TCCs showed the mutation in only about 40% of the cases. Further studies of clinical outcome are ongoing to evaluate the prognostic relevance of this finding. Additional factors, such as breed and anatomical site of the neoplasm may also influence the prevalence of BRAF mutation.

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