猫胆脂瘤

王帆

Cholesteatoma in a cat

猫胆脂瘤

作者：Akash Alexander, Paul Mahoney, Emma Scurrell and Stephen Baines

翻译：王帆

 

Abstract 

Case summary A 14-year-old neutered female Burmese cat was referred for investigation of a caudal oropharyngeal mass. CT showed a thin walled cyst-like structure filling and expanding from the right tympanic bulla. Histopathology showed fragments of mildly dysplastic squamous epithelium and aggregates of keratin. These findings were considered consistent with a diagnosis of cholesteatoma.

Relevance and novel information To the best of our knowledge, this is the first reported case of a cholesteatoma in a cat. Cholesteatoma should be considered a differential diagnosis for cats presenting with a caudal oropharyngeal mass, a history of chronic ear disease or a history of previous, surgically managed middle ear disease. Advanced imaging and biopsies should be considered important in the diagnosis of these lesions.

Keywords: Cholesteatoma; oropharyngeal mass; ear; otitis; ventral bulla osteotomy

摘要

病例概述 一只14岁已绝育雌性缅甸猫因口咽尾侧肿块就诊和检查。CT显示右侧鼓泡有一薄壁囊肿样结构充盈扩张。组织病理学提示轻度发育不良的鳞状上皮碎片和角蛋白聚集。这些发现被认为与胆脂瘤的诊断一致。

相关性和新信息 据我们所知，这是第一例报告的猫胆脂瘤。对于有口咽尾侧肿物、慢性耳部疾病史或中耳外科疾病史的猫，应考虑胆脂瘤的鉴别诊断。高级影像学和活组织检查对于确诊此病变至关重要。 

关键词:胆脂瘤、口咽肿块、耳部、耳炎、腹侧鼓泡截骨术

 

Case description

病例描述 

A 14-year-old neutered female Burmese cat was referred for investigation of a caudal oropharyngeal mass.

一只14岁已绝育雌性缅甸猫因口咽尾侧肿块就诊。

 

Three weeks prior to referral the cat presented to the primary care veterinarian for lethargy, altered vocalisation, snorting when eating and masticating with one side of the mouth. A temperature of 39.4°C was noted, as well as gingival recession on the upper-left carnassial tooth. The teeth were scaled, polished and three extractions were performed. At this time, ventral deviation of the soft palate was noted on the right-hand side. Following dental treatment, the clinical signs resolved. A rightsided nasopharyngeal polyp had been removed by traction via the pharynx when the cat was 8 months old, followed by a ventral bulla osteotomy (VBO).

在转诊前三周，这只猫因为嗜睡、声音改变、进食时打鼾和用一边嘴咀嚼而被送到首诊兽医那里。体温39.4°C，左上裂齿牙龈萎缩。进行洁牙、抛光，并拔除三颗牙齿。此时，右侧发现软腭腹侧偏曲。经牙科治疗后，临床症状消失。在猫8个月大时，经咽牵引切除右侧鼻咽息肉，随后行腹侧鼓泡截骨术(VBO)。

 

On presentation, physical examination revealed a firm, immobile right-sided caudal oropharyngeal mass, a mild right-sided head tilt and a body condition score of 3.5/9. Auscultation revealed mild stridor with the point of maximum intensity over the larynx. The remainder of the examination was unremarkable. Laryngoscopy and pharyngoscopy immediately after induction of anaesthesia, but prior to intubation, revealed a hypoplastic soft palate with a markedly curved caudal free border that was situated rostral to the epiglottis. The mass had an intact mucosa over its surface, which extended into the pharynx.

体格检查显示右侧口咽尾侧肿物坚实，不能移动，头部轻度向右侧倾斜，体况评分为3.5/9。听诊显示轻度喘鸣，最大喘鸣点位于喉部。其余检查未见异常。麻醉诱导后立即进行喉镜和咽喉镜检查，但在插管前，发现软腭发育不良，有明显弯曲的尾端游离边界，位于会厌口侧。肿块表面有完整的黏膜，并延伸至咽部。

 

CT (General Electric Brightspeed 16, Model: 2335179- 2) showed a thin walled cyst-like structure filling and expanding from the right tympanic bulla. This extended rostrally through the site of the previous VBO, into the right retropharyngeal space, bulging medially into the caudal nasopharynx and oral cavity (Figure 1). The mass measured 13 mm (dorsoventral) by 13 mm (lateromedial) by 27 mm (rostrocaudal). A relatively consistent attenuation (HU68) was noted throughout the mass, apart from a small central region of increased attenuation (HU85). A CT scan following administration of contrast revealed enhancement of the thin wall of the structure but not of the contents (Figures 1–4). Mild enlargement of the right mandibular lymph node, widespread bronchitis and right middle lung lobe atelectasis were also seen.

CT显示右鼓泡充盈扩张一个薄壁囊肿样结构。该肿物经上一个VBO部位向口侧延伸，进入右侧咽后间隙，向内侧膨出进入鼻咽尾侧和口腔(图1)。肿物测量值为13mm(背腹侧)、13mm(内侧侧)、27mm(上尾侧)。除了一小块中央区域的衰减增加(HU85)外，整个肿块的衰减相对一致(HU68)。CT扫描显示薄壁结构增强，但内容物没有增强(图1-4)。右下颌淋巴结轻度肿大，大面积支气管炎，右肺中叶肺不张。

 

TruCut needle biopsies were taken from the mass via the oral cavity, which yielded pale/tan homogeneous, friable tissue. On otoscopic examination of the right ear, material similar to that of the biopsies could be seen in the deeper parts of the horizontal canal extending into the middle ear cavity, and grab biopsies were taken via the external ear canal. The cat was discharged with meloxicam (Metacam 0.1 mg/kg PO q24h; Boehringer Ingelheim).

经口腔对肿块进行TruCut针活检，发现苍白/棕褐色均匀，易碎组织。右耳耳镜检查，水平耳道深入中耳腔可见与活检相似的材料，经外耳道抓取活检。使用美洛昔康(0.1 mg/kg PO, q24h)。

 

Histopathological examination of the samples showed sections consisting of amorphous necrotic cellular debris with foci of suppurative inflammation. Small clumps of bacteria were also noted, along with rare fragments of mildly dysplastic squamous epithelium and aggregates of keratin. These findings were considered consistent with a diagnosis of cholesteatoma. No cytology was performed on submitted samples.

样本的组织病理学检查显示切片由无定形坏死细胞碎片和化脓性炎症灶组成。观察到小区域的细菌，伴随着罕见的轻度发育不良的鳞状上皮碎片和角蛋白聚集。这些发现被认为与胆脂瘤的诊断一致。未对提交的样本进行细胞学检查。

 

Treatment options, including a ventral bulla osteotomy or a lateral bulla osteotomy, with or without a total ear canal ablation, were discussed with the owner. The owner elected to not pursue surgical removal of the cholesteatoma. A course of potentiated amoxicillin (12.5 mg/kg PO q12h) for 14 days was started based on the histopathological findings of suppurative inflammation in the middle ear.

治疗方案包括腹侧鼓泡截骨术或外侧鼓泡截骨术，伴或不伴全耳道消融术。宠主决定不进行手术切除胆脂瘤。根据中耳化脓性炎症的组织病理学检查结果，开始使用阿莫西林增效剂(12.5 mg/kg PO, q12h)， 连用14天。

 

The cat lived for a further 3 years, during which time it was treated over 30 times by its primary care veterinarian with antibiotics for recurrent episodes of suppurative otitis. The cat was eventually euthanased after developing neurological signs including knuckling and loss of sensation on all four limbs, inability to ambulate, anorexia and facial rubbing, but it was not reported whether these signs were lateralised. A post-mortem examination was not permitted.

这只猫又活了3年，在此期间，它的首诊兽医用抗生素治疗了30多次复发化脓性耳炎。这只猫在出现了包括四肢关节和感觉丧失、无法行走、厌食和面部摩擦等神经症状后，最终被安乐死，但没有报告这些症状是否为单侧。未进行尸检。

 

Discussion

讨论

To our knowledge this is the first reported case of a cholesteatoma in a cat.

据我们所知，这是第一例报告的猫胆脂瘤。

 

The term cholesteatoma is well described in the literature but is potentially a misnomer as these lesions are not neoplastic in nature and do not contain cholesterol. A cholesteatoma describes a benign keratinising squamous cell cyst. Histologically, they are made up of a keratinised stratified squamous-lined cyst, filled with squamous debris. Visually, they often appear as cysts with a pearly white content. Cholesteatomas grow invasively, destroying neighbouring structures as keratin debris accumulates within the cyst’s lining.

胆脂瘤一词在文献中有很好的描述，但可能是一个用词不当，因为这些病变在本质上不是肿瘤，不含胆固醇。胆脂瘤描述为良性角质化鳞状细胞囊肿。组织学上，它们由角化的鳞状分层囊肿组成，充满鳞状碎片。在视觉上，它们通常表现为具有珍珠白色内容物的囊肿。胆脂瘤侵袭性生长，随着角蛋白碎片在囊肿内衬内积聚，破坏邻近结构。

 

Cholesteatomas are defined as either congenital or acquired. In human medicine, cholesteatoma is a rare clinical finding with an incidence of three and 9.2 per 100,000 population in children and adults, respectively. In the veterinary literature there is ambiguity with the terms cholesteatoma and cholesterol granuloma. At times they are used synonymously, particularly in equine medicine. However, cholesterol granulomas consist of cholesterol clefts embedded in granulation tissue and the suspected aetiology is different from cholesteatomas.

胆脂瘤被定义为先天性或后天的。在人医中，胆脂瘤是一种罕见的临床发现，儿童和成人的发病率分别为每10万人3例和9.2例。在兽医文献中，胆固醇脂瘤和胆固醇肉芽肿的术语存在歧义。有时它们被用作同义词，特别是在马医学中。然而，胆固醇肉芽肿由嵌入肉芽组织的胆固醇结晶组成，其病因与胆脂瘤不同。

 

Proposed theories for the formation of a cholesteatoma include invagination of the tympanic membrane into the middle ear and displacement of squamous epithelium from the external ear canal into the middle ear.In a gerbil model, it was shown that the tympanic membrane was the origin of the cholesteatoma epithelium. Attempts to induce cholesteatomas in cats through ligation of the Eustachian tube or ligation of the external auditory canal have been unsuccessful. All current theories suggest that chronic inflammation and bacterial infection are important predisposing factors for the development and growth of cholesteatomas. The presence of bacteria on the histopathological evaluation of the lesion in this report suggests that chronic infection could have played a role in the formation of this cholesteatoma.

胆脂瘤形成的理论包括鼓膜内陷至中耳和鳞状上皮从外耳道移位至中耳。在沙鼠模型中，鼓膜是胆脂瘤上皮细胞的起源。通过结扎耳咽管或外耳道诱导猫胆脂瘤的尝试均未成功。目前所有的理论都表明，慢性炎症和细菌感染是胆脂瘤发生和生长的重要易感因素。在本报告中，病变的组织病理学检查中发现细菌，提示慢性感染可能在胆脂瘤的形成中起作用。

 

Historically, canine cholesteatomas have been reported to be secondary complications of aural surgery, particularly total ear canal ablation with lateral bulla osteotomy (TECA-LBO), in which inflamed or infected epithelium could be left behind after surgery. In the absence of surgery, ongoing infection and inflammation have also been shown to be a primary cause of cholesteatomas such as in otitis externa and media. In this case the presence of the middle ear polyp, its effect on the middle ear and external ear canal, or the surgical procedure (ventral bulla osteotomy) to manage this could have contributed to the formation of the cholesteatoma.

历史上，犬胆脂瘤已被报道为耳外科手术的继发并发症，特别是全耳道切除加外侧鼓泡截骨术(TECA-LBO)，手术后可能留下发炎或感染的上皮细胞。在不手术的情况下，持续的感染和炎症也被证明是胆脂瘤的原发病因，如外耳炎和中耳炎。在这种病例中，中耳息肉的存在，其对中耳和外耳道的影响，或外科手术(腹侧鼓泡截骨术)可能导致胆脂瘤的形成。

 

In this case, there were few clinical signs related to the mass. However, given the location and the destructive, invasive nature of cholesteatomas, it is possible for affected animals to present with a range of clinical signs. In a case series of 20 dogs the observed clinical signs on presentation included head tilt, asymmetrical facial palsy, ataxia, nystagmus, circling and asymmetrical atrophy of the temporalis and masseter muscles. Given the proximity of the vestibulocochlear nerve and the facial nerve the majority of signs are likely attributed to their involvement. Four of the dogs in the case series had pain on opening their mouth or were unable to open their mouth fully. Respiratory noise and effort was also reported in the study. Mass lesions in the nasopharyngeal region have been associated with respiratory compromise and noise due to an obstructive effect. In this case, the previously performed VBO may have allowed the mass to extend ventrally out of the previous bulla osteotomy site and therefore cause less destruction laterally or medially relative to the bulla. This may have impacted on the clinical signs present in this case.

在这个病例中，几乎没有与肿块相关的临床症状。然而，考虑到胆脂瘤的位置和破坏性、侵袭性，患病动物可能会表现出一系列临床症状。在20只犬的病例中，观察到的临床症状包括头倾斜、不对称面瘫、共济失调、眼球震颤、颞肌和咬肌旋转和不对称萎缩。由于接近前庭耳蜗神经和面神经，大多数症状可能归因于他们的参与。在这个系列的案例中，有四只犬在张嘴时感到疼痛，或者不能完全张嘴。呼吸噪音和费力也在研究中被报道鼻咽区域的肿块病变与由于阻塞作用而造成的呼吸损害和噪音有关。在本例中，先前施行的VBO可能使肿物向腹侧延伸出鼓泡截骨区域向前延伸，因此相对于鼓泡，在外侧或内侧造成的破坏较小。这可能影响了本例的临床症状。

 

Diagnosis of this condition may be delayed as epidermoid cysts can often be present for a prolonged period of time before there is accumulation of sufficient keratin within them, or the surrounding inflammation and infection is significant enough to cause clinical signs. Bacterial infection of the central nervous system has been linked to an aural cholesteatoma that eroded through the petrous portion of the temporal bone, eventually causing infection of the vestibulocochlear ganglion. In this case it is unclear if the neurological signs seen prior to euthanasia were caused by the cholesteatoma as no further investigation was undertaken at the time and a necropsy was not performed. Meningitis has been reported in two dogs that had bone lysis into the cranial fossa; one of these was also found to be septic.

这种疾病的诊断可能会延迟，因为表皮样囊肿通常会存在很长一段时间，直到它们内部积累了足够的角蛋白，或者周围的炎症和感染足以引起临床症状。中枢神经系统的细菌感染与耳胆脂瘤有关，该肿物侵袭颞骨岩部，最终导致前庭耳蜗神经节感染。在本例中，尚不清楚安乐死前看到的神经症状是否由胆脂瘤引起，因为当时没有进行进一步的调查，也没有进行尸检。据报道，在两只犬中有骨溶解到颅窝的脑膜炎;其中一例还被发现是败血症。

 

Initial investigation into this case involved the use of contrast CT imaging to identify the location and nature of the lesion. In both human and veterinary medicine CT scans have been shown to be the imaging modality of choice. Changes visible on the CT include osteoproliferation, osteolysis of the bulla, expansion of the bulla and bone lysis in the petrosal portion of the temporal bone. Local lymphadenomegaly may also be seen, as was noted in this case. Changes can also be seen in the ipsilateral temporomandibular joint with the presence of a periosteal reaction, sclerosis or osteoproliferation. MRI is an alternative imaging modality, particularly when neurological signs predominate. Typical MRI findings are material that is isointense compared with brain tissue on T1-weighted images and of mixed intensity on T2-weighted and fluid-attenuated inversion recovery sequences. There is no post-contrast enhancement of the content, but enhancement of the lining of the bulla may be seen. MRI is being utilised more in human medicine as a radiation-free form of imaging to detect cholesteatomas, particularly in paediatric patients.

对这个病例的初步调查涉及到使用CT造影对比来确定病变的位置和性质。在人类和动物医学中，CT扫描已被证明是首选的影像检查。CT上可见的改变包括骨增生、鼓泡骨质溶解、鼓泡扩张及颞骨岩部骨质溶解。局部淋巴结肿大也可见，如本例所示。同侧颞下颌关节也出现骨膜反应、硬化症或骨增生的变化。MRI是一种可替代的影像检查方式，特别是当神经症状为主时。典型的MRI表现为T1加权图像与脑组织相比为等强度，T2加权和液体衰减反转恢复序列为混合强度。造影后未见内容物增强，但可见鼓泡内膜增强。MRI作为一种无辐射影像方式在人类医学中被更多地用来检测胆脂瘤，特别是在儿科患者中。

 

It may be that many patients with a cholesteatoma may go undiagnosed owing the relative lack of clinical signs early on in the disease, the similarity of these signs to those of chronic otitis externa/otitis media and the lack of investigation into the underlying cause of the clinical signs. Even if not yet clinically significant, early diagnosis and surgical intervention of a cholesteatoma has been shown to improve outcome and prognosis, and early intervention may be curative.

许多胆脂瘤患病动物可能未得到诊断，原因可能是该疾病的早期临床症状相对缺乏，这些症状与慢性外耳炎/中耳炎相似，以及缺乏对临床症状的潜在病因的调查。即使还没有临床意义，早期诊断和手术干预的胆脂瘤已被证明能改善结果和预后，早期干预可能治愈。

 

The mainstay of management of patients with cholesteatoma is surgical intervention, often paired with longterm antimicrobial use. In dogs the main surgical intervention described is either a TECA-LBO or a VBO, with the former being performed more commonly. Particular care is needed to ensure as complete an excision as possible, and use of advanced imaging modalities helps with surgical planning and achieving complete removal of abnormal tissue. There was no difference reported in outcome based upon the surgical approach taken. Complete removal of the abnormal epithelium was deemed important, but was often difficult owing to its tight adherence to the abnormal bone. The use of rongeurs, high-speed burrs and a carbon dioxide laser were used to maximise removal.

胆脂瘤患病动物的主要的管理方式是手术干预，往往需要长期使用抗菌药物。在犬中，主要的手术干预是TECA-LBO或VBO，其中前者更常见。需要特别的护理，以确保尽可能完整的切除，并使用高级影像检查，有助于手术计划和实现完全切除异常组织。根据所采取的手术方法，没有报告结果的差异。完全切除异常上皮被认为是重要的，但由于其与异常骨的紧密粘附，常常是困难的。使用咬骨钳、高速磨钻和二氧化碳激光来最大限度地清除。

 

However, recurrence of clinical signs or persistence of clinical signs has been reported in around 50% of patients treated. Greci et al reported a confirmed recurrence in 4/11 dogs, and a fifth one was suspected but was not investigated. Time to recurrence ranged from 2–13 months. In the series of 20 dogs, 19 of which were surgically managed, nine showed resolution of clinical signs during the follow-up period that ranged from 3–95 months. Signs of middle ear disease, otodynia, head tilt and discomfort opening the mouth were present in the cases that recurred. Advanced disease at the time of first presentation was the main factor associated with recurrence. Factors that are significantly associated with recurrence after surgery include pain or difficulty with opening the jaw, bulla lysis, neurological disease or bone lysis within the squamous and petrosal portions of the temporal bone evident on CT imaging. Short-term complications of surgery related to damage to the facial nerve were thought to be caused during curettage of the middle ear cavity, but these often resolved. The large medial component of the cholesteatoma in this case, which encroached on the oropharynx, meant that repeat VBO may not have provided adequate access to and drainage of this part of the mass and as a result may not have helped to resolve the condition.

然而，据报道，在治疗的患者中，约有50%的临床症状复发或临床症状持续。Greci等人报道了确诊4/11只犬的复发，还有5只犬被怀疑复发，但没有进行调查。复发时间为2-13个月。在这组20只犬中，其中19只接受了手术治疗，其中9只在3-95个月的随访期间临床症状得到了缓解。复发者有中耳疾病、耳痛、头倾斜和开口不适的症状。首次就诊时的晚期疾病是与复发相关的主要因素。与术后复发显著相关的因素包括:疼痛或颌骨开口困难、鼓泡溶解、神经系统疾病或CT图像显示的颞骨岩部的骨溶解伴有鳞状上皮。与面神经损伤相关的手术短期并发症被认为是在刮除中耳腔时引起的，但这些往往会得到解决。本例胆脂瘤较大的内侧部分侵袭口咽，这意味着重复VBO可能无法提供足够的通路和引流这部分肿块，因此可能无助于解决问题。

 

Conclusions

结论

Cholesteatoma should be considered a differential diagnosis for cats presenting with a caudal oropharyngeal mass and, as a result, investigation with advanced imaging should be performed. Cats with a history of chronic ear disease or surgical management of middle ear disease that present with deficits of the facial or vestibulocochlear nerve that do not resolve or become chronic should be investigated for potential cholesteatoma.

胆脂瘤应被视为猫口咽尾侧肿物的鉴别诊断，因此，应进行高级影像学检查。有慢性耳部疾病史或中耳疾病外科治疗史的猫，其面部或前庭耳蜗神经损伤不消退或变成慢性，应调查是否有潜在的胆脂瘤。

 

 

Figure 1 Dorsal plane reconstruction of the post-contrast study (soft tissue window) demonstrating the thin rim of contrast enhancement surrounding the mass as it extends through the rostral wall of the right tympanic bulla

图1造影后背侧重建(软组织窗口)显示肿物沿右鼓泡吻侧壁延伸时，围绕肿物的薄的增强边缘。

 

 

Figure 2 Sagittal plane reconstruction of the post-contrast study (soft tissue window) through the plane of the right tympanic bulla, showing loss of the rostral bulla wall due to rostral extension of the mass

图2造影后矢状面重建(软组织窗口)穿过右鼓泡平面。

 

 

Figure 3 Transverse image of the post-contrast study (bone window) demonstrating the loss of the right bony bulla wall

图3造影后横像(骨窗)显示右侧鼓泡壁缺失

 

 

Figure 4 Transverse image of the post-contrast study (soft tissue window) demonstrating the mass bulging medially into the nasopharynx and oral cavity

图4造影后横像(软组织窗)显示肿物向鼻咽和口腔内侧膨大

 

 

 

曾医生

无穷小南瓜

bateer578

疫情期间好好学习