McEwan Stephanie A, Sykes Jane E
Departments of Medicine and Surgery, Biological Science and Psychological Science, University of California, Irvine, CA, USA.
Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California-Davis, Davis, CA, USA.
JFMS Open Rep. 2022 Mar 25;8(1):20551169221074624. doi: 10.1177/20551169221074624. eCollection 2022 Jan-Jun.
An indoor-only 6-year-old spayed female domestic cat was evaluated for a history of stertorous respiration. Skull radiographs revealed increased soft tissue density within the caudal aspect of the left nasal cavity. CT and rhinoscopy revealed a mass lesion in the choana, plus a smaller lesion, nearly completely occluding flow through the nasal passages. Rhinoscopy was used to collect a biopsy specimen from a fleshy, tan-yellow mass visualized in the caudal nasopharynx. Histopathology was diagnostic for species infection and systemic antifungal therapy with fluconazole was initiated. Following a series of discordant results, serum samples were submitted to a veterinary diagnostic laboratory that utilized a cryptococcal antigen latex agglutination system with pretreatment of serum with pronase. Twenty-three months after the initial diagnosis, the cat's serum cryptococcal antigen titer declined to 1:5 and the cat has responded well to continuing treatment.
This case illustrates challenges associated with discordant test results for cryptococcal antigen among laboratories. Discordancies may be due to differences in assay design, or the underlying disease state itself, or whether serum is pre-treated with pronase; with some tests relying on the training and experience of the operator if the cryptococcal antigen detection test requires a subjective interpretation. It also resolves some confusion in the literature related to the assay types available and terminology used to describe them, and emphasizes the importance of considering cryptococcosis as an important differential for cats with upper respiratory signs, without nasal discharge, even if the cat is kept exclusively indoors.
对一只6岁室内饲养的已绝育雌性家猫进行评估，该猫有呼吸粗重的病史。颅骨X光片显示左鼻腔后部软组织密度增加。CT和鼻镜检查显示后鼻孔有一个肿块病变，还有一个较小的病变，几乎完全阻塞了鼻腔通道。鼻镜检查用于从鼻咽后部可见的肉质、棕黄色肿块采集活检标本。组织病理学诊断为真菌感染，并开始用氟康唑进行全身抗真菌治疗。在一系列结果不一致后，血清样本被送往一家兽医诊断实验室，该实验室使用隐球菌抗原乳胶凝集系统，并先用链霉蛋白酶预处理血清。初次诊断23个月后，猫的血清隐球菌抗原滴度降至1:5，且该猫对持续治疗反应良好。
本病例说明了实验室之间隐球菌抗原检测结果不一致所带来的挑战。结果不一致可能是由于检测方法设计的差异、潜在疾病状态本身，或者血清是否用链霉蛋白酶预处理；如果隐球菌抗原检测需要主观解释，一些检测还依赖于操作人员的培训和经验。它还解决了文献中关于可用检测类型和用于描述它们的术语的一些混淆，并强调了即使猫仅在室内饲养，对于有上呼吸道症状但无鼻分泌物的猫，将隐球菌病作为重要鉴别诊断的重要性。
