一例吉娃娃犬大面积进行性色素性病毒斑块

王帆

Extensive progressive pigmented viral plaques in a Chihuahua dog

一例吉娃娃犬大面积进行性色素性病毒斑块

作者：John S. Munday, Andrea T.H. Lam and Mary Sakai

翻译：徐晋

Extensive exophytic pigmented viral plaques developed on a Chihuahua dog causing pruritus and discomfort. Neither the medical treatments used nor a papillomavirus vaccine resulted in clinical improvement. Laser surgery removed some plaques, yet others developed. This case illustrates the difficulty in treating viral plaques and the progressive nature of this disease.

一只吉娃娃犬身上出现了大面积外生性色素性病毒斑块，引起瘙痒和不适。使用的药物治疗和乳头瘤病毒疫苗均未带来临床改善。激光手术清除了一些斑块，但其他斑块依然发展。该病例说明了治疗病毒性斑块的困难和本病的发展特点。

Introduction

介绍

Canine pigmented viral plaques are caused by papillomavirus (PV) infection. Viral plaques rarely undergo spontaneous remission and can become quite numerous. While there are rare reports of progression to neoplasia, pigmented plaques are mostly of cosmetic concern. The present report describes a Chihuahua that developed plaques that were extensive, proliferative and caused significant discomfort. Multiple treatments were attempted, and none was curative.

犬色素性病毒斑块由乳头瘤病毒(PV)感染引起。病毒斑块很少自行缓解，可大面积发展。发展为肿瘤的报告很少，色素性斑块大多是美观问题。本报告描述了一只吉娃娃出现大面积斑块，为增生性且引起明显不适。尝试多种治疗均未治愈。

Case report

病例报告

A 2-year-old female spayed Chihuahua initially developed small dark flat plaques on her head. These progressed slowly until, by six years of age, the plaques had progressed in size and distribution across the body, and began to coalesce into patches. Pigmented viral plaques were diagnosed by histological examination as a result of the presence of well-demarcated areas of moderate acanthosis, a characteristic scalloped appearance and large quantities of intralesional melanin. At this time, the dog began to show signs of pruritus and discomfort. Treatments used without significant improvement included Thuja occidentalis extract (per os, every 12 h), vitamin A (8,000 IU/kg, p.o., every 24 h, RiteAid; Camp Hill, PA, USA), 5% imiquimod cream (twice weekly, Aldara; Bausch Health, Laval, Canada), azithromycin (6 mg/kg, p.o., every 12 h), and interferon alfa-2b (4,255 IU/kg, p.o., every 24 h, Roadrunner Pharmacy; Phoenix, AZ, USA).Three years later, the plaques had enlarged to 3 cm in diameter, and were exophytic and verrucous. The lesions resembled pigmented warts and covered approximately 40% of the skin with only the dorsum and lateral thoraces spared (Figure 1). A plaque was submitted to Georgetown University, Washington, DC, USA (http://copv.info/ 8.html) to identify the causative PV type for anti-PV vaccine. PCR using specific primer sets for canine papillomavirus (CPV) types 1 to 10 amplified only CPV2 DNA from the sample.

一只2岁已绝育雌性吉娃娃最初头部出现小的深色扁平斑块。这些病变发展缓慢，直到6岁时，斑块增大且遍布全身，并开始融合成斑片。通过组织学检查诊断为色素性病毒斑块，特征为存在边界清晰的中度棘皮症、典型的扇形外观和病变内大量黑色素。同时，犬开始出现瘙痒和不适症状。治疗包括北美香柏提取物（口服，每12h一次）、维生素A（8000 IU/kg，口服，每24h一次）、5%咪喹莫特乳膏（每周两次）、阿奇霉素（6 mg/kg，口服，每12h一次）和α-2b干扰素（4255 IU/kg，口服，每24h一次），都没有得到明显改善。3年后斑块直径扩大至3 cm，且呈向生长、疣状。病变类似色素疣，覆盖约40%的皮肤，仅背部和胸外侧没有病变（图1）。将一块斑块送检至美国华盛顿特区乔治敦大学鉴定致病PV类型以定制抗PV疫苗。使用犬乳头瘤病毒(CPV)1-10型的特异性引物组进行PCR，从样品中仅扩增出CPV2 DNA。

A proportion of the plaques were removed or debulked during two rounds of laser ablation at six week intervals. This was followed by subcutaneous administration of a vaccine against CPV2 in accordance with the protocol supplied with the vaccine. While the laser surgery decreased the number of lesions, the dog continued to develop new plaques elsewhere on the body. An additional sample was taken for repeat histological and molecular testing.

在间隔6周的两轮激光消融过程中，去除或消减掉一部分斑块。随后根据疫苗提供的方案皮下接种抗CPV2疫苗。虽然激光手术减少了病变的数量，但该犬身体其他部位继续出现新的斑块。重新采集样本重复进行组织学和分子学检测。

Histological examination revealed numerous disorganised papillary projections that were lined by moderately hyperplastic epidermis surrounding a core of dermis containing dilated lymphatics and melanophages (Figure 2). The dermis contained a minimal inflammatory reaction.Increased melanin and clumping of keratohyalin granules was visible in the epidermis. The epidermis was covered by marked orthokeratosis with keratin apparently trapped between the papillary projections.

组织学检查显示大量杂乱的乳头状突起，被中度增生的表皮包围，真皮核心包含扩张的淋巴管和噬黑色素细胞（图2）。真皮层有极轻微的炎症反应。表皮层可见黑色素增多，透明角质颗粒成团。表皮层覆盖明显的正角化性角化过度，角质明显陷入乳头突起之间。

Consensus PCR primers were used to amplify PV DNA from a plaque as described previously. CPV4 DNA was amplified from the plaque by the MY09/11 and CP4/5 primers. No PV DNA was amplified from the plaque by the FAP59/64 primers, although CPV2 DNA was amplified from a positive control. At the time of writing, the dog continues to develop new plaques with the larger ones appearing to cause discomfort, pruritus and limiting mobility.

使用共识的PCR引物从斑块中扩增PV DNA，如前所述。MY09/11和CP4/5引物从斑块中扩增出CPV4 DNA。尽管从阳性对照中扩增出CPV2 DNA，但FAP59/64引物未从斑块中扩增出PV DNA。在撰写本文时，犬继续出现新的斑块，较大的斑块似乎引起不适、瘙痒和活动受限。

Discussion

讨论

This case is novel owing to the high proportion of the body that was affected and the apparent discomfort that the plaques caused. In addition, in contrast to the sessile plaques described previously, the lesions in the present case were exophytic, resembling pigmented warts. Pruritus has been associated with plaques in only one previous case. While CPV2 DNA was amplified from initial biopsy tissue, subsequent molecular testing detected CPV4 only. As CPV4 commonly causes plaques, the unusual clinical presentation in this dog suggests an unusual host response to a common PV type.

该病例是新病例，机体患病部位比例较高且斑块引起明显不适。此外，与之前描述的无蒂斑块相比，本病例中的病变为外生性，类似于色素疣。在既往病例中，仅1例瘙痒与斑块相关。虽然从首次活检组织中扩增出CPV2 DNA，但随后的分子检测仅检测到CPV4。由于CPV4通常引起斑块，该犬的异常临床表现表明宿主对常见PV类型的异常反应。

The early disease onset and severity of lesions suggests a genetic immunodeficiency. Pugs and vizslas appear to be predisposed to viral plaques, although, to the best of the authors’ knowledge, this is the first report in a Chihuahua. The dog appeared otherwise healthy, suggesting that any immune-deficiency was limited to the immune response against PVs. In people, a genetically mediated inability to mount an immune response against infection of the skin by PVs characterises the disease epidermodysplasia verruciformis (EV). As was seen in the Chihuahua, people with EV develop multiple, flat, pigmented plaques at a young age, with lesions becoming more extensive and wart-like over time.

疾病的早期发作和病变的严重程度提示遗传免疫缺陷。巴哥犬和维希拉猎犬似乎容易出现病毒斑块，但据作者所知，这是首例吉娃娃的报告。犬在其他方面表现健康，表明任何免疫缺陷仅限于抗PV的免疫应答。在人类，基因介导的无法对PV感染皮肤产生免疫应答是疣状表皮发育不良(EV)疾病的特征。如在吉娃娃所见，EV患犬在年轻时出现多发性、扁平、色素性斑块，随着时间的推移，病变变得更加广泛和疣状。

Laser removal of pigmented viral plaques previously has been reported to be curative. In the present case, this treatment was able to ablate a proportion of lesions, yet additional lesions developed. None of the medical treatments used in the present case appeared to change the clinical course of the disease. Azithromycin has been reported to promote resolution of canine warts, although this treatment has not been effective in some subsequent cases. Interferon was suggested as a treatment for canine viral plaques, while vitamin A and imiquimod were reported to be useful in treating human PV-induced lesions. Although not curative, it remains possible that these treatments could have slowed plaque growth.

以前有报道称激光去除色素性病毒斑块可治愈。在本病例中，该治疗能够消融一部分病变，但又出现了新的病变。本病例中使用的药物治疗似乎均未改变临床病程。据报道，阿奇霉素可促进犬疣的消退，但该治疗在随后的一些病例中无效。干扰素被认为是治疗犬病毒斑块的方法，而维生素A和咪喹莫特有报道可用于治疗人PV诱导的病变。尽管无法治愈，但这些治疗仍有可能减缓斑块生长。

CPV2, which previously has not been reported to cause pigmented plaques, was detected by initial molecular testing. This may have been present as an incidental finding, which would explain the apparent lack of efficacy of the CPV2 vaccine for treatment of these lesions. However, whether or not PV vaccines are useful as treatments for PV-induced lesions is currently unclear and a recent large scale study in which vaccines against human PV types were used to treat human gential warts did not show efficacy. Cryotherapy and topical treatment with tigilanol tiglate gel are additional treatments suggested for canine pigmented viral plaques, and were not attempted in the present case. Currently there is no treatment known to be definitively effective for all cases of EV in people and this also may be true for canine pigmented viral plaques.

本病例在初次分子检测时检测到CPV2，而CPV2之前未见引起色素斑块的报道。这可能是偶然结果，可以解释CPV2疫苗治疗这些病变明显缺乏有效性的原因。然而，PV疫苗是否可用于治疗PV诱导的病变目前尚不清楚，最近一项使用抗人PV类型疫苗治疗人生殖器疣的大规模研究显示无疗效。冷冻治疗和替格洛醇凝胶外部治疗是建议用于犬色素性病毒斑块的替代治疗，在本病例中未尝试。目前，尚无已知对人类所有EV病例明确有效的治疗方法，犬色素性病毒斑块也可能是如此。

Figure 1. Pigmented viral plaques cover approximately 40% of the skin of the dog with canine papillomavirus 4 (CPV4) infection. The plaques are ≤4 cm in diameter and larger lesions are verrucous in nature.

图1. 感染犬乳头瘤病毒4(CPV4)的犬，约40%的皮肤覆盖色素性病毒斑块。斑块直径≤4 cm，较大病变呈疣状。

Figure 2. Histological findings suggestive of canine viral pigmented plaque.

(a) Papillated projections of acanthotic epidermis are supported by a fibrovascular core that contains dilated lymphatics (arrows) and oedema. Extensive orthokeratotic hyperkeratosis is present between the adjacent papillary projections. Haematoxylin & eosin, *100.

(b) Epidermis is moderately hyperplastic and contains increased quantities of melanin. Clumping of keratohyalin granules is prominent within the superficial layers of the epidermis (arrows). H&E, *200.

图2. 组织学提示犬病毒性色素斑块。

(a)表皮层棘皮症的乳头状突起，由含有扩张淋巴管（箭头）和水肿的纤维血管核心支撑。邻近乳头突起之间存在广泛的正角化性角化过度。苏木精和伊红，*100。

(b)表皮中度增生，黑色素增多。透明角质颗粒明显聚集在表皮浅层内（箭头）。H&E,*200.

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