獣医臨床皮膚科 16 (2): 61–65, 2010

Case Report

Bacterial Pseudomycetoma (Botryomycosis) in an FIV-positive Cat

FIV陽性猫にみられた細菌性偽菌腫（ボトリオミセス症）の１例

Tae Murai1)*, Kyohei Yasuno2), Kinji Shirota2, 3) 1)Kinder-Care Veterinary Clinic, 2)Research Institute of Biosciences and 3)Laboratory of Veterinary Pathology, Azabu University

村井 妙 1)* 安野恭平 2) 代田欣二 2, 3)

1)キンダーケア動物病院，2)麻布大学附置生物科学総合研究所，3)麻布大学獣医病理学研究室

Abstract: A 2.5-year-old spayed female domestic short-haired cat presented with more than a month’s history of a thickly crusted, purulent draining lesion on the shoulder area. Prior to the lesion’s formation, the cat had been repeatedly scratching the shoulder. Histological examination of skin biopsy specimens revealed both discrete and confluent pyogranulomas with fibroplasias and characteristic granules composed of gram-positive cocci surrounded by an eosinophilic amorphous substance. The histopathological findings were consistent with bacterial pseudomycetoma. The skin lesion was successfully treated with systemic and topical administration of antibiotics for about 4 months. However, occasional scratching continued, leading to the development of a small erosion in the same area. The present cat was antigen-positive for feline immunodeficiency virus, and it showed symptoms potentially caused by feline immunodeficiency syndrome. Decreased immune competence might contribute to the pathogenesis of bacterial pseudomycetoma. Key words: bacterial pseudomycetoma, botryomycosis, cat

要 約：2.5歳齢，避妊済みの雑種猫が，頚背部に著しく厚い痂疲を伴う排膿性皮疹を呈し来院した。 病変は当初激しいそう痒から始まり，やがて掻爬部位に一致して瘻孔の形成を認めた。病変部の病 理組織学検査では，線維化と好酸球性の無定形物質に取り囲まれた多数のグラム陽性球菌からなる 特徴的な顆粒がみられ，単独あるいは融合した化膿性肉芽腫が認められた。それらの病理組織学的 所見は，細菌性偽菌腫に合致するものであった。病変は，抗生物質の全身投与および外用による治 療で，4ヵ月後にはほぼ治癒したが，ときおり掻爬により小さな病変が発現した。症例猫は猫免疫不 全ウイルス抗原陽性であり，しばしば猫免疫不全症候群と考えられる症状を呈しており，免疫能の 低下が細菌性偽菌腫の形成に関与した可能性が考えられた。 キーワード：細菌性偽菌腫，ボトリオミセス症，猫

(Jpn J Vet Dermatol 2010, 16 (2): 61–65)

*Correspondence to: Tae Murai (Kinder-Care Veterinary Clinic) 848-12 Kamidono, Kanuma, Tochigi 322-0045, Japan TEL 0289-65-6699 FAX 0289-63-5099 E-mail: [email protected] * 連絡先：村井 妙（キンダーケア動物病院） 〒 322-0045 栃木県鹿沼市上殿町 848-12 62 Feline Bacterial Pseudomycetoma

Fig. 1. Gross appearance of the skin lesion at the first visit. Fig. 2. Skin lesion on the shoulder area after removing the Note the thick crust on the shoulder area. crust. Punch biopsy specimens were taken from several sites of the lesion.

Table 1. Results of Hematological and Biochemical Analyses Case Report RBC 533 × 104 /µl Hb 6.7 g/dl WBC 13,100/µl BUN 16 mg/dl A 2.5-year-old spayed female domestic short-haired cat Lym 4,100/µl Cre 1.0 mg/dl presented with more than a month-long history of a thickly Eos 700/µl Glu 192 mg/dl Other 8,300/µl TP 7.7 g/dl crusted, purulent draining lesion on the shoulder area (Fig. PLT 12.5 × 104 /µl Alb 2.6 g/dl 1). The cat had free access to the outdoors and had been Ht 20.30% ALT 2.6 g/dl kept together with three other household cats. The skin ALP <130 IU/dl lesion initially started with intense pruritus, and with FRA 214 µmol/l marked scratching progressed to an erosive and ulcerative purulent lesion. The owner treated the cat for a month with a commercially available ointment containing unknown disinfectants; however, the lesion worsened. Introduction At the initial visit, the cat was emaciated (body weight: 2.4 kg), and its oral mucosa was pale in color. No other Bacterial pseudomycetoma (botryomycosis, cutaneous significant abnormalities were found. The results of bacterial granuloma) is a chronic pyogranulomatous hemogram and serum biochemistry indicated anemia bacterial infection of soft tissue that is commonly referred (Table 1). Serological examination for infectious diseases to as a nodular or draining tract lesion11). It has been was positive for FIV antigen and negative for feline reported in various animals, including cats and dogs, as leukemia virus, feline infectious peritonitis virus, well as in humans1, 2, 11, 12), but it is rarely seen in cats. The Bartonella henselae and Toxoplasma gondii. Cytological incidence of eumycetoma and pseudomycetoma caused examination of the exudates revealed numerous cocci, by fungi in cats suggests that some predisposing factors bacilli, neutrophils and macrophages. Careful skin such as heritable susceptibility or immune deficiency scrapings were negative for fungi and ectoparasites. might be involved in these mycotic diseases13). A similar Fungal culture was negative. The crust separated easily predisposition may be suspected for development of from the lesion, and a skin biopsy of the underlying bacterial pseudomycetoma in cats. ulcerated tissue was performed (Fig. 2). The present paper reports the outcome of bacterial Histopathological examination of the skin lesion pseudomycetoma in a cat that was antigen-positive for revealed that the epidermis was ulcerated and intense feline immunodeficiency virus (FIV). pyogranulomatous inflammation composed of neutrophils and macrophages had developed in the dermis and subcutis. There were many discrete and confluent Murai, T., et al. 63

Fig. 4. High-power view of a pyogranuloma. The granule was surrounded by numerous neutrophils and composed of both basophilic granular/amorphous substance and eoosinophilic amorphous material. HE. Fig. 3. Histological features of the biopsy Bar = 100 µm. specimen. Many discrete pyogranulomas with central irregularly shaped granules were present (arrows). Hematoxylin and eosin (HE). Bar = 200 µm. pyogranulomas with central granules (Fig. 3) composed of numerous gram-positive cocci surrounded by an eosinophilic amorphous substance that sometimes showed a clubbed or radiating appearance known as the Splendore– Hoeppli reaction (Figs. 4 and 5). A few pyogranulomas contained thin hair fragments in their centers (Fig. 6). These histopathological findings were consistent with bacterial pseudomycetoma (botryomycosis). Differential diagnoses for this lesion included Fig. 5. The granule contained numerous gram-positive cocci actinomycosis, mycobacteriosis, deep fungal infection, surrounded by amorphous substance. Gram stain. neoplasia, and foreign body reaction. Infection due to Bar = 50 µm. excessive scratching was suspected. Initial treatment consisted of subcutaneous injection of cefovecin at 8 mg/kg every 2 weeks. The cat was kept a bandage. Administration of a hypoallergenic diet was strictly indoors during the course of therapy. The lesion started in order to rule out adverse food reaction, but this was cleaned with chlorhexidine solution and gentamycin did not alter the scratching behavior. The lesion was cured ointment was applied topically. The lesion responded almost 4 months after the first visit. The cat occasionally quickly to antibiotic therapy; however, the scratching scratched the same area afterwards, but the contaminated behavior continued (Fig. 7A). Six weeks later, a bacterial skin lesion did not recur and additional treatment and culture was performed from a small recurrent erosive lesion, protection were not needed (Fig. 7B). The cat showed and Pseudomonas spp. and Bacillus spp. were isolated. serious anorexia for a fairly long time during and after Based on antibiotic sensitivity testing, oral doxycycline at therapy. The cat died about 2 years after the first visit, 5 mg/kg/day was begun. However the cat vomited after presenting anorexia, progressive weight loss, anemia and each dose and became weak afterward. Systemic antibiotic neurological symptoms that were consistent with feline therapy was discontinued and the lesion was protected by immunodeficiency syndrome due to FIV infection. 64 Feline Bacterial Pseudomycetoma

Fig. 6. Pyogranulomas containing a thin fragment of hair Fig. 7. Gross appearances of the skin lesion at 4 weeks (A) (arrow). Bar = 50 µm. and 9 months (B) after initiation of treatment.

Discussion are primary characteristics. Special stains and culturing may be necessary in some cases. Histopathological Bacterial pseudomycetoma is a bacterial granulomatous findings show pyogranulomatous inflammation, and a disorder of the skin that mimics fungal infection both Splendore–Hoeppli reaction—bright eosinophilic clinically and histopathologically11). However, it is not a material surrounding bacterial colonies, representing an mycotic infection as the name implies, and the antigen–antibody reaction—may be a unique granulomatous reaction presumably develops due to an manifestation of bacterial pseudomycetoma12). imbalance in the host immune response. In humans, occasional predisposing factors of bacterial There is some confusion among the terms mycetoma, pseudomycetoma include diabetes mellitus, malnutrition eumycotic mycetoma, pseudomycetoma, bacterial and various states of immunodeficiency, including human mycetoma and bacterial pseudomycetoma11). To immunodeficiency virus infection3–7, 18, 20). According to understand bacterial pseudomycetoma more precisely, it several reports, there must be a precise interaction between is helpful to first review mycetoma and pseudomycetoma the virulence of the organisms and the host response for recognized in humans, dogs and cats16). Mycetomas are bacterial pseudomycetoma to develop2, 3, 5, 8–11, 19). The caused by bacteria and fungi14, 15), and clinical features present cat may have been in an immune-compromised consist of the following three visible factors: 1) formation condition owing to FIV infection. The lesion initially of a dermal nodule or granuloma in the lesion; 2) existence started with intense pruritus and was treated by the owner of small granules composed of organisms in the tissue; with commercially available ointment containing and 3) formation of draining tracts. In contrast to unknown disinfectants for over a month without success. eumycotic mycetomas (i.e., mycotic or fungal No grains or granules in the suppurative exudates were mycetomas), pseudomycetomas appear as ulcerated found grossly or microscopically. dermal nodules consisting of pyogranulomatous Usually, complete surgical excision is the inflammation and fungal hyphae16). Pseudomycetomas recommended treatment, since antibiotics generally lack true cement material in the tissue grains, have cannot penetrate granulomas1, 3, 8, 9). In addition, systemic abundant Splendore–Hoeppli reaction material and fewer antibiotic administration over a period of at least 4 to 8 hyphal filaments, and display sequential developmental weeks is also recommended. Surgery was not performed stages of granulomas13, 14, 17). in this case because of possible impaired immunity and Definitive diagnosis of bacterial pseudomycetoma is concern over potentially poor post-operative wound based on careful examination of a skin lesion by cytology healing. Antibiotic therapy by injection effectively healed and skin biopsy; formation of the dermal nodules or the ulcerated lesion. granulomas with small tissue granules and draining tracts Various underlying factors may be involved in the Murai, T., et al. 65

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