Evaluation of histopathology as a diagnostic method for equine sarcoids and treatment options

Abstract

Equine sarcoids are the most common neoplasias of the skin in equines and especially relevant in horses. They present clinically as locally invasive, single or more frequently, multiple lesions with a heterogenous appearance, which highly depends on their clinical nature. Equine sarcoids are morphologically divided into 6 classes: occult, verrucous, nodular, fibroblastic, mixed, and malignant/malevolent. In diagnostics it is essential, to differentiate the sarcoids, as some forms are more resistant to therapy and have a tendency to transform into more aggressive forms. Histopathology is considered the gold-standard in diagnosis of sarcoids but the risk for aggravating the lesions when taking a biopsy is high. This study aims to evaluate if histopathology remains as the gold-standard a diagnostic tool and compare its frequency of use with other laboratory diagnostic tools like fine needle aspiration, polymerase-chain-reaction and immunohistochemistry. Additionally, the frequency of use and success rates of different treatment options in correlation with various types of sarcoids were evaluated. Data was obtained by a questionnaire that was answered by 26 equine veterinarians. 88.5% of the study population did use histopathology as a diagnostic method, most frequently for verrucous form (84.6%), mixed (76.9%), fibroblastic and nodular (53.8%). Furthermore, histology was most frequently rated “very good” (41.7%) in terms of precision and utility and none of the questioned veterinarians rated it “unreliable/ not helpful” in diagnosis of sarcoids. Fine needle aspiration was only used by 3.8%, polymerase-chain-reaction by 14.6 % and immunohistochemistry was only used by 13.3%. Surgical removal was the most frequently chosen treatment (92.3%), with a prevalence of use in nodular (61.5%) sarcoids. According to the results obtained, this study concludes that histopathology, despite the risks a biopsy poses, is still the gold-standard in diagnostics of equine sarcoids and surgical removal is the preferred treatment for these persistent neoplasias.

Hobuste sarkoidid on üks sagedasemaid nahakasvajaid hobuslastel ja seda eelkõige hobustel. Kliiniliselt esinevad need üksikult lokaalselt invasiivsena või pigem hulgikoldeliselt erinevate vormidena, mis on tugevas sõltuvuses kliinilisest olemusest. Hobuste sarkoidid on morfoloogiliselt jagatud 6 vormi: peidetud, näsaline, sõlmeline, fibroblastiline, segavorm ja pahaloomuline. Sarkoidide korrektne diferentseerimine on diagnostikas oluline, kuna mõned vormid on ravile resistentsemad ja omavad võimalust muutuda ravijärgselt pahaloomulisemaks. Patohistoloogiat loetakse heaks diagnoosimise meetodiks, kuigi proovivõtt võib mõjutada kasvaja olemust. Käesoleva uurimistöö eesmärgiks oli hinnata patohistoloogiat kui kõige edukamat meetodit, aga rõhutada ka peennõela aspiraadi, polümeraasahelreaktsiooni või immunohistokeemia tähtsust. Töös on uuritud erinevate sarkoidi tüüpide raviks valitud meetodi ja selle edukuse suhet. Andmeid koguti küsimustikule vastamise teel, millele vastas 26 hobuse loomaarsti. Vastustest selgub, et 88.5% arstidest ei kasuta patohistoloogiat kui diagnostilist meetodit, seda peamiselt näsalise (84.6%), segavormi (76.9%), fibroblastilise ja sõlmelise vormi (53.8%) diagnostikas. Lisaks märgiti histoloogia väga heaks meetodiks täpsuse ja kasulikkuse poolest ning puudusid märkimised meetodi mitte abistavaks tunnistamise kohta. Peennõela aspiraat oli kastutusel ainult 3.8%, polümeraasahelreaktsioon 14.6% ja immunohistokeemia 13.3% juhtudel. Kirurgiline eemaldamine oli kõige enam valitud ravimeetod (92.3%), sealhulgas sõlmeliste vormide korral (61.5%). Vastavalt seatud eesmärkidele näitas antud uurimus patohistoloogia tähtsust hobuste sarkoidide diagnostikas, seda hoolimata koeproovide võtu riskist. Kirurgilist eemaldamist loetakse kui eelistatumat antud kasvajate raviviisi.