A new study, published in the Journal of Small Animal Practice (JSAP), showed that transverse sectioning confers significant benefits and complements traditional vertical sectioning in histological assessment of canine hair follicle diseases. The study was funded by BSAVA-PetSavers, the charitable division of the British Small Animal Veterinary Association.
The study titled “Transverse sectioning in the evaluation of skin biopsy specimens from alopecic dogs” assessed whether the use of transverse sectioning in histological processing could enhance the diagnostic benefit from skin biopsies of dogs with alopecic disorders.
Skin biopsy specimens were taken from skin lesions in 31 alopecic dogs clinically suspected of having a range of atrophic, dysplastic and inflammatory diseases of the hair follicles and or adnexal glands. Following fixation, samples were bisected vertically and one half was embedded in the traditional vertical orientation, whilst the other half of the sample was sectioned transversely. The sections were reviewed independently in triplicate in random order and investigators were blinded to previous diagnosis using a standard checklist pro-forma. The kappa statistic was used to assess the agreement between the histological findings for the criteria assessed in the paired vertical and transverse sections.
Professor Ross Bond of the Royal Veterinary College, corresponding author for the paper, said: “As expected, the team [Dr Anke Hendricks, Dr Kim Stevens, Dr Harriet Brooks-Brownlie,Professor Janet Patterson-Kane and Professor Ross Bond] observed substantial overlap in the principal pathological features in the 90 paired vertical and transverse sections, but there were also numerous examples where one or other of the two sectioning planes yielded superior visualisation of key features.
“Follicular inactivity scores in transverse sections significantly exceeded those in vertical sections. Agreement between the two sectioning planes was moderate for infundibular hyperkeratosis and dermal inflammation, fair for sebaceous gland abnormalities and pigment clumping, but slight for follicular activity. Vertical sectioning demonstrated diagnostically important epidermal pathology and dermal thinning, whereas transverse sectioning enhanced assessment of the hair growth phase, follicular structure and architecture, and focal luminal or mural folliculitides.”
The authors added: “This study indicates that transverse sectioning frequently complements traditional vertical sectioning when evaluating canine follicle diseases. Transverse sectioning a portion of the biopsy may be especially valuable in evaluating the phase of hair growth in the specimen and when key histopathological features, such as inflammatory processes, affect relatively small numbers of adnexa within the specimen. It is also of value in evaluating the number, size and arrangement of follicles within compound follicles and follicular units.”
Nicola Di Girolamo, Editor of JSAP concluded: “This relatively simple modification of sample processing can provide further diagnostic information with no additional risk for the patient, and as such has a relevant application in a large number of dogs.”
BSAVA-PetSavers is funded solely by charitable donations and has invested more than £2 million in vital clinical research and training programmes over the past 40 years to advance clinical investigations into pet animal medicine and surgery. For further information on BSAVA-PetSavers visit the website here.
An early online version of the article has been published online here. It is open access and can be freely accessed by anyone.
The Journal of Small Animal Practice is published monthly and access to all articles is free for BSAVA members. For information on how to become a BSAVA member visit the website here.
1R .Bond, A. Hendricks, J. Patterson-Kane, K. Stevens and H. W. Brooks Brownlie (2020) Transverse sectioning in the evaluation of skin biopsy specimens from alopecic dogs. Journal of Small Animal Practice. Available at: https://onlinelibrary.wiley.com/doi/10.1111/jsap.13243