OBSERVATION Granulomatous Skin Infection Caused by Malassezia pachydermatis in a Dog Owner Yi-Ming Fan, MD; Wen-Ming Huang; Shun-Fan Li; Guo-Feng Wu, MM; Kuan Lai, MM; Rong-Yi Chen, MM Background: Malassezia pachydermatis is part of the nor- flammatory granuloma, numerous purple-red round or mal cutaneous microflora of dogs and many other mam- ovoid spores in the superficial necrotic tissue, and sparse mals. M pachydermatis has not yet been reported as an red spores in the dermis. The skin lesions healed after agent that causes skin infection in humans, although it oral fluconazole and cryotherapy. has been found to cause fungemia and other nosoco- mial infections in preterm newborns and immunocom- Conclusions: Definite diagnosis of M pachydermatis– promised adults. induced skin infection principally depends on the results of fungal culture and histologic examination, Observations: Malassezia pachydermatis was isolated and the combination of oral fluconazole and adjunc- from the facial granuloma of a healthy woman and her tive cryotherapy seems to be an effective therapeutic dog’s skin scrapings and cerumen. The yeast identity was regimen. established by standard methods and scanning electron microscopy. A skin biopsy specimen showed chronic in- Arch Dermatol. 2006;142:1181-1184 HE GENUS MALASSEZIA, M pachydermatis is frequent in wild and comprising 10 distinct domestic carnivores, including dogs, species, is principally cats, bears, ferrets, and foxes; less fre- recovered from the skin of quent in rhinoceros, pigs, primates, pin- mammals and birds but nipeds, horses, and birds; and undetec- Tseldom from the environment.1,2 Mal- ted in rodents and lagomorphs.1,2 Human assezia pachydermatis, Malassezia furfur, skin is commonly colonized by lipid- Malassezia globosa, and Malassezia sym- dependent Malassezia yeasts but rarely podialis are generally considered to be by M pachydermatis.3 Malassezia pachy- the main species associated with clinical dermatis has not yet been reported as an diseases.1 Malassezia pachydermatis, the agent that causes skin infection, al- only non–lipid-dependent species of the though it has been found to cause funge- genus Malassezia, was first isolated from mia and other nosocomial infections in the scales of an Indian rhinoceros (Rhi- preterm newborns and immunocompro- 2,4-7 noceros unicornis) with exfoliative der- mised adults. We isolated a strain of matitis by F. D. Weidman in 1925 and M pachydermatis from an immunocom- named Pityrosporum pachydermatis. With petent woman with facial granuloma in the synonymy of Malassezia (proposed April 2004. To our knowledge, this is the by H. Baillon in 1889) and Pityrosporum first report of M pachydermatis–induced (proposed by R. Sabouraud in 1904) skin infection in humans. being increasingly recognized and accepted in 1984 with anteriority for the REPORT OF A CASE generic Malassezia, P pachydermatis was then adopted as M pachydermatis, a name first introduced by C. W. Dodge in 1935 A 46-year-old woman presented with an Author Affiliations: 2 Department of Dermatology, and accepted by M. A. Gordon in 1976. asymptomatic papule on her face in Affiliated Hospital of The importance of M pachydermatis has January 2004. The lesion enlarged gradu- Guangdong Medical College, been recognized in both veterinary and ally and appeared erosive and exudative Zhanjiang, Guangdong, China. human medicine.2 Skin colonization by after self-treatment with topical applica- (REPRINTED) ARCH DERMATOL/ VOL 142, SEP 2006 WWW.ARCHDERMATOL.COM 1181 ©2006 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/30/2021 A B Figure 1. Patient before and after treatment. A, A verrucous plaque on the right side of the face and a hemispheroid nodule on the left ala nasi. B, After treatment, hypopigmented scar on the right side of the face. Figure 2. Secretion smear showing numerous gram-positive, yeastlike Figure 3. Biopsy specimen showing purple-red round or ovoid spores in the polymorphous spores (gram stain; original magnification ϫ1000). superficial necrotic tissue (periodic acid–Schiff stain; original magnification ϫ1000). tion of medicinal herbs. A similar lesion occurred on the left ala nasi 2 months later. She came to the Depart- purple-red round or ovoid spores in the superficial ment of Dermatology at the Affiliated Hospital of necrotic tissue and sparse red spores in the dermis Guangdong Medical College in April 2004. She had no (Figure 3). The lesional secretions and the dog’s skin history of local trauma and had kept a pet dog for 9 scrapings and cerumen were cultured using Sabouraud months. At examination, there was a painless verrucous dextrose agar (SDA) at 27°C, and yeastlike milky colo- plaque (5.2ϫ3.1 cm) on the right side of her face that nies grew on SDA supplemented with olive oil at 2 weeks was covered with black and greasy crusts and sur- and on SDA without lipid supplement at 3 weeks. The rounded by 2 nodules, and a yellowish hemispheroid colony surface was matte, convex, and wrinkled, and the nodule (0.5 cm in diameter) on the left ala nasi undersurface was flat. The surface color was ivory at first (Figure 1A). Local lymphadenopathy was absent. and darkened from yellow to brown with age. A direct Potassium hydroxide preparation from skin lesions smear showed small and less refractive yeast cells and showed no fungal elements, but gram staining revealed spores. The fungus grew well on oily SDA at 27°C and numerous gram-positive, yeastlike polymorphous 37°C, grew poorly at 41°C, and did not grow at 4°C or spores (Figure 2). A biopsy specimen showed chronic 8°C. Catalase test results were negative. inflammatory granuloma. Epidermal hyperkeratosis, Scanning electron microscopy (Philips XL30; Philips acanthosis, and obvious follicular dilation were appar- Holland Eindhoven, the Netherlands) revealed that the ent, with microabscesses composed of neutrophils in cells were globose, ovoid, ellipsoidal, or cylindrical in some of the hair follicles. The dermal inflammation was shape and 2.35 to 2.6 µmϫ2.07 to 2.1 µm in size. Uni- characterized by diffuse infiltration of primarily lym- polar blastic development was observed (eg, the daugh- phocytes, plasmocytes, and histiocytes, with occasional ter cell was separating from the cell wall of the mother eosinophils, neutrophils, and multinucleated giant cells. cell at one end). The bud body was 1.39ϫ1.37 µm in Periodic acid–Schiff (PAS) staining revealed numerous size, the collarette was 1.3 µm in breadth, and the base (REPRINTED) ARCH DERMATOL/ VOL 142, SEP 2006 WWW.ARCHDERMATOL.COM 1182 ©2006 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/30/2021 was circular and 0.36 µm thick. The characteristics of these neonatal intensive care unit (NICU), M pachydermatis in- colonies were compatible with those of M pachyderma- fection and colonization appeared in 8 infants with very tis. Purified tuberculin test results were strongly posi- low birth weights who had various underlying diseases tive (ie, vesiculation at the inoculation site at 72 hours). during a 6-month period.7 In addition, the source of the Other laboratory investigations did not reveal extracu- outbreak caused by M pachydermatis and its prophylac- taneous disease or immunosuppression. tic measures have been investigated. The clinical iso- The patient received 4 antituberculotics (isoniazid, rif- lates of M pachydermatis in an NICU were nosocomial ampicin, pyrazinamide, and streptomycin sulfate) for 2 for all strains isolated, with both patients and incubator months because the results of direct examination and fun- surfaces being genetically indistinguishable; regular hy- gal culture using SDA without lipids were negative and gienic measures cannot adequately remove or kill the the skin lesions were still augmented. According to posi- yeasts, which may persist on glass surfaces for at least 2 tive findings of fungal culture and PAS staining, she was months despite regular cleaning of the incubators.9 How- then treated with itraconazole (0.2 g/d), 10% potassium ever, M pachydermatis was likely introduced into the NICU iodide solution (30 mL/d), and ciprofloxacin (0.4 g/d) from health care workers’ hands after being colonized from for 2 weeks. Although the lesions stopped enlarging, the pet dogs at home; careful hand washing by health care results of direct examination and fungal culture were still workers before and after contact with patients can effec- positive. Finally, she received fluconazole (0.2 g/d) for tively prevent the introduction and nosocomial trans- 10 weeks, ciprofloxacin (0.4 g/d) for 1 week, and liquid mission of the pet-associated yeast, since all cultures from nitrogen cryotherapy 5 times. The skin lesions com- the nursing staff and attending physicians were nega- pletely disappeared, leaving hypopigmented scars tive for the organism after hand-washing practices had (Figure 1B). No relapse has occurred at 15 months of fol- been improved.6 low-up. Lipid supplementation is not an absolute require- ment for the growth of M pachydermatis, but the addi- tion of lipid material to the culture medium can COMMENT enhance its growth.1,2 It grows at temperatures from 25°C to 41°C and seems to be sensitive to the cold.2 Malassezia pachydermatis is part of the normal cutane- Malassezia pachydermatis is characterized by cream- ous microflora of dogs and many other mammals.1 Mal- colored colonies with dry and smooth surfaces and assezia pachydermatis was first believed to be the patho- short ovoid to ellipsoidal cells.2 The mode of conidium gen of otitis externa in the dog by B. A. Gustafson in ontogeny was unipolar budding on a broad base, with 1955 and the cause of canine chronic dermatitis by R. a collarette.10 Malassazia pachydermatis is easily identi- Dufait in 1983.2 In view of its importance as a canine fied by the colonies’ morphologic and growth features pathogen, the carriage of M pachydermatis in dogs has and by microscopic examination, but our patient was been widely surveyed.