Surgical margins in the veterinary cancer patient

In veterinary oncologic specimens, histopathology is the gold standard for determining adequacy of excision. Despite limitations of this technique, the pathologist's interpretation of margin status significantly impacts patient management, including indications for adjuvant therapy. This article aims to summarize peer-reviewed literature as it relates to histologic margin evaluation in veterinary cancer patients. The value of histologic tumour-free margins and technical factors influencing histopathologic margin outcomes are also discussed. We review alternative strategies for determining excisional status, and discuss how an evolving understanding of tumour biology might inform clinical and research perspectives on surgical margins. In doing so, we aim to provide context and a stimulus for future investigations into this important yet incompletely understood topic.

Fatal Streptococcus anginosus-associated pneumonia in a captive Sumatran orangutan (Pongo abelii)

BACKGROUND

Bacterial infections commonly affect the lungs and air sacs of orangutans; culture and identification is rarely performed and may have clinical relevance.

METHODS

Necropsy, histopathology and bacterial culture were performend on a captive adult male Sumatran orangutan with chronic air sacculitis. Bacterial speciation was confirmed by sequencing of the 16s-23s ribosomal DNA spacer region.

RESULTS

Necropsy revealed severe suppurative pneumonia. Moderate growth of Streptoccocus anginosus was recovered from the lungs.

CONCLUSIONS

This is the first report of S. anginosus as a cause of fatal suppurative pneumonia in a non-human primate.

An immunohistochemical study of vitamin D receptor expression in canine cutaneous mast cell tumours

The active form of vitamin D (1alpha, 25-dihydroxycholecalciferol; calcitriol) has potent anti-neoplastic activity in the management of a number of human malignancies. Despite promising data to suggest that calcitriol is an effective adjunct to current chemotherapy modalities, the role of calcitriol in animal neoplasia is poorly understood. Vitamin D inhibits growth of canine mast cell tumours (MCTs) in vitro, presumably due to ligand-mediated activation of the vitamin D receptor (VDR). The aim of the present study was to examine immunohistochemically the expression of the VDR by reactive and neoplastic canine cutaneous mast cells. Expression was graded according to frequency, intensity and score (frequency x intensity). VDR expression was found in all samples containing reactive mast cells (n=9), and in 67 of 69 (97%) MCTs selected from each of the three Patnaik grades. The frequency and score of VDR labelling was greater in MCTs compared with reactive mast cells (P=0.0005 and 0.001, respectively). There was no difference in VDR frequency between the MCT grades, but the frequency of labelling in grade 3 MCTs was higher than for reactive mast cells (P=0.001). There was no association between tumour mitotic index and any of the three VDR variables (all P>0.16). VDR is widely expressed by reactive and neoplastic canine mast cells in vivo. VDR expression is unlikely to represent an independent prognostic factor, but its presence within biopsy specimens might be used to identify patients that are suited to high-dose vitamin D therapeutic trials.