a case of feline phaeohyphomycosis due to fonsecaea pedrosoi (pages 297–301)

8/10/2019 A Case of Feline Phaeohyphomycosis Due to Fonsecaea Pedrosoi (Pages 297301)

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2001 Blackwell Science Ltd 297

Veterinary Dermatology2001, 12, 297301

BlackwellScience,Ltd

Case report

A case of feline phaeohyphomycosis due toFonsecaea pedrosoi

ALESSANDRA FONDATI,* MARIA GRAZIA GALLO, ERICA ROMANO and

DOLORES FONDEVILA*

*Facultat de Veterinria, Universitat Autnoma de Barcelona, Barcelona, Spain;

Facolt di Medicina Veterinaria, Universit degli Studi di Torino, Torino, Italy;

Private Practitioner, Rome, Italy

(Received9 May2000; accepted13 March2001)

Abstract The first report of a case of feline phaeohyphomycosis due to Fonsecaea pedrosoiis presented.

Fonsecaea pedrosoiis an aetiologic agent of both human phaeohyphomycosis and chromoblastomycosis. In our

cat, the lesion was confined to the skin and appeared as a firm swelling on the bridge of the nose. Diagnosis was

based on histological examination of a cutaneous biopsy and fungal culture of a tissue sample on Sabourauds

dextrose agar. Further diagnostic tests failed to reveal an underlying immunosuppression. Two treatment cycles

with itraconazole, at the oral dose of 5 mg kg1given twice daily, induced complete clinical remission, but

relapses occurred.

Keywords:cat, Fonsecaea pedrosoi, mycosis, phaeohyphomycosis.

INTRODUCTION

Phaeohyphomycosis is an infection of animals andhumans caused by dematiaceous fungi. Dematiaceous

fungi are defined as those that have melanin or

melanin-like pigment in their cell walls.1They are a

heterogeneous group of organisms unified by their pro-

duction of melanin pigments. In phaeohyphomycosis

these fungi develop in the host tissues in the form of

dark-walled dematiaceous septate mycelial elements.2

The dematiaceous elements, in tissue, appear as either

irregularly septate hyphae, branched or unbranched,

or as yeast-like cells, solitary or in short chains.

Fourteen different fungal species belonging to 12

genera

3

have been documented as agents of felinephaeohyphomycosis and include, among others,

Alternaria sp., Cladophialophora sp., Curvularia sp.,

Drechslera sp., Exophiala sp., Moniliella sp., Ochro-

conis sp., Phialophora sp., Scolecobasidium sp. and

Stemphyliumsp. These fungi are found widely in nature

and live ubiquitously in soil, usually associated with

plant material. Traumatic implantation of fungal

elements leads to chronic granulomatous infection of

viable cutaneous tissues. Variably ulcerated nodules

develop most commonly on the face and distal extre-

mities. Systemic spreading of fungal elements is rare.

This report describes a case of phaeohyphomycosis

due to Fonsecaea pedrosoiin a cat. To our knowledge

this is the first description of feline phaeohyphomycosisdue to F. pedrosoi.

CASE REPORT

A 4-year-old, neutered male, Domestic Long Hair cat was

presented with a 7-month history of a progressive, non-

pruritic swelling on the bridge of the nose accompanied

by sneezing. The owner explained that the swelling

initially had a black dot on the surface and that a pre-

sumptive wasp sting preceded it by a few weeks. The cat

had been treated unsuccessfully with systemic antibiotics.At dermatological examination, a firm and hard

swelling was present on the bridge of the nose. The

swelling was nonpainful on palpation and the over-

lying skin was normal (Fig. 1). At physical examination

the cat was otherwise healthy.

Differential diagnosis included eosinophilic granu-

loma, foreign body reaction, deep fungal and/or

bacterial infection and neoplasia. The diagnostic plan

included fine-needle aspiration cytology and cutaneous

biopsy and, depending on the results, further mycolo-

gical and bacteriological cultures, haematological, bio-

chemical, serological and radiographic evaluations.

Cytological examination of air-dried preparations stainedwith Diff-Quik revealed degenerated neutrophils

and macrophages. Histological examination of haema-

toxylin and eosin (H&E)-stained sections revealed a

Correspondence: Alessandra Fondati, Facultat de Veterinria,

Universitat Autnoma de Barcelona, 08193 Bellaterra; Barcelona,

Spain. Tel.: +34 93 5811421, Fax: +34 93 5813142, E-mail:

[email protected]


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2001 Blackwell Science Ltd, Veterinary Dermatology, 12, 297301

dermal nodule consisting of an accumulation of

macrophages, neutrophils, plasma cells and lymphocytes

surrounding brown-pigmented and thick-walled fungal

yeast-like cells and hyphae. Hyphae appeared branched

and closely septate (Fig. 2). Multinucleated giant

cells were also present. Inflammatory cells were pre-

sent in the surgical margins. On tissue sections, fungal

elements stained strongly with periodic acid Schiff

(PAS) (Fig. 3) and Gomoris methenamine silver

(GMS) stains. The histopathological diagnosis waspyogranuloma due to dematiaceous fungi. Based on

the clinicalpathological findings the diagnosis was

phaeohyphomycosis.

Further diagnostic evaluation was performed to rule

out underlying systemic diseases, immunosuppression

and deep fungal invasion. Both complete blood count

and serum chemistry profile were within normal limits

for the reference laboratory. Enzyme-linked immuno-

assays (ELISAs) to detect feline leukaemia viral antigen

and antibody to feline immunodeficiency virus were

negative. Nasal, thoracic and abdominal radiographs

did not show abnormalities.

Fungal cultures of cutaneous tissue specimens wereperformed to identify fungal organisms. The epidermis

was removed from a cutaneous biopsy specimen, the

sample was then ground aseptically, placed in sterile

saline and the suspension was used to inoculate

Sabourauds dextrose agar plates. The organism was

identified as F. pedrosoiin the Department of Animal

Production, Ecology and Epidemiology, Faculty of

Veterinary, Turin (Prof. M.G. Gallo), where it is depos-

ited in a mycological collection.

Cultures gave rise in 3 weeks to velvety, dark olive

green colonies with shallow radial grooves (Fig. 4).

The colony reverse was deep black. Because of great

colonial variation within the species F. pedrosoi, fungalidentification was obtained through microscopic exam-

ination of conidia (Fig. 5). Microscopically, conidial

structures of both Rhinocladiella (acropleurogenus)

and Cladosporiumtypes were observed. The Rhinocla-

diellatype of conidia was characterized by sympodial

conidiophores bearing brown, single-celled, oval

conidia in their upper portion. The conidia were pro-

duced on short denticles. Some conidia produced

secondary conidia. This represents a salient feature to

differentiate the genus Fonsecaeafrom Rhinocladiella,

which produces a single row of conidia around a conid-

iophore. The Cladosporiumtype of conidia was char-

acterized by very short conidial chains obtained byprogressive budding, as observed in the genus

Cladosporium. Moreover, flask-shaped phialides pro-

vided by distinctive collarettes, typical of the genus

Figure 1. Feline phaeohyphomycosis due to Fonsecaea pedrosoi.

Swelling on the bridge of the nose. Photo reproduced from A

Practical Guide to Dermatology, 1999 Merial.

Figure 2. Histopathology. Brown-pigmented, thick-walled yeast-

like fungal cells (arrowhead) and irregularly septate hyphae (arrow)

surrounded by macrophages, neutrophils, plasma cells andlymphocytes (H&E 400).

Figure 3. Histopathology. Numerous, slightly brown-pigmented,

periodic acid Schiff (PAS)-positive fungal elements (PAS 400).

Figure 4. A velvety, olive green fungal colony of Fonsecaea pedrosoi

cultured on Sabourauds dextrose agar.


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Phaeohyphomycosis in a cat 299

Phialophora, were observed (Fig. 6). All these features

are reported as characteristic of F. pedrosoi.4 6

Because of the anatomical site, complete resection of

the lesion was considered unlikely, and therefore anti-

fungal chemotherapy was preferred. The cat was

treated with oral itraconazole at a dosage of 5 mg kg1

given twice a day. A complete response to therapy was

observed with return to clinical normality in 1 month.

Itraconazole therapy was well-tolerated and was main-

tained for a further 3 months. Six months after the ini-

tial treatment was withdrawn a relapse occurred and

itraconazole therapy was reinstated at the same dosage.

Complete clinical remission was obtained in 1 month

and therapy was maintained for a further 5 months. A

second relapse was observed 9 months after therapywithdrawal. Unfortunately, at this time, the cat was lost

to follow-up.

DISCUSSION

Dematiaceous fungi may cause phaeohyphomycosis,

black-grain eumycotic mycetoma and chromoblasto-

mycosis.1Phaeohyphomycosis is an uncommon infec-

tion in European countries and occurs more frequently

in tropical and subtropical regions. However, cases

of feline and human phaeohyphomycosis have beenrecorded in Europe.1,3,7 Phaeohyphomycosis is an

ever-increasing presence in human disease and, as the

population of immunocompromised patients con-

tinues to grow, the incidence of phaeohyphomycosis,

particularly the disseminated disease, will most likely

continue to increase.8Over the years, the list of fungi

causing human phaeohyphomycosis has grown con-

siderably and will likely continue to expand. Feline

subcutaneous phaeohyphomycosis is not usually asso-

ciated with immunosuppression and the number of

cases recorded remains relatively low. 3,9Nevertheless,

the list of fungi causing feline phaeohyphomycosis has

also grown in recent years.Black-grain eumycotic mycetomas are characterized

clinically by the triad of tumefaction, draining sinuses

and the presence of brown granules in the discharge

from sinuses.10Examination of granules reveals struc-

tures that vary, depending on the fungus, from ones

composed of septate, branching hyphae to those con-

sisting of a compact mass of rounded cells. Curvularia

sp. and Phaeococcus sp.9have been isolated in feline

black-grain eumycotic mycetomas.

Chromoblastomycosis is a chronic cutaneous and

subcutaneous infection characterized by the presence

in tissue of brown-walled, round, nonbudding fungal

elements called sclerotic bodies. Sclerotic bodies are

typically divided by intersecting septa in more than one

plane, longitudinal and transverse, and they represent

the distinctive histopathological feature of human

chromoblastomycosis.1 Chromoblastomycosis has

been described only in humans, most commonly inthe form of verrucous plaques and nodules on feet

and legs.

Aetiologic agents of human chromoblastomycosis

include, Cladophialophora carrionii, Exophiala jeanselmei,

Exophiala spinifera, Fonsecaea pedrosoi, Phialophora

verrucosaand Rhinocladiella aquaspersa.1

Fonsecaea pedrosoi is the most common aetiologic

agent of human chromoblastomycosis in tropical and

subtropical regions of America, and in Asia, Australia

and Europe, mostly the eastern countries.11However,

F. pedrosoi may cause both human chromoblasto-

mycosis and phaeohyphomycosis.

1

Because the same species of fungi can cause different

clinicalpathological entities, and due to the confusing

taxonomy of the commonly implicated organisms in

diseases caused by dematiaceous fungi, in our view, the

change of nomenclature advocated by the Inter-

national Society for Human and Animal Mycology

in 1992 should be applied. According to this change,

the conventional clinical diagnosis should be followed

by the name of the fungus,12 therefore our case

would have been accurately described as a dermal

pyogranuloma caused by Fonsecaea pedrosoi.

The diagnosis of phaeohyphomycosis in our case

was based on the clinicalpathological findings. Adiagnosis of black-grain eumycotic mycetoma was

ruled out based on the absence of two of the clinical

findings typical of mycetoma, which are draining tracts

Figure 5. Slide culture of Fonsecaea pedrosoi. Conidial struc-

tures Rhinocladiella type bearing two rows of conidia, (a) one

playing the role of conidiogenuos cell and (b) one conidial

structure Cladosporium type. Phialides Phialophora type are

shown in (c).

Figure 6. Slide culture of Fonsecaea pedrosoi. Flask-shaped phialide

of Phialophoratype (arrow).


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300 A. Fondati et al.


and granules in the exudate. Typical sclerotic bodies,

which are considered characteristic of human chromo-

blastomycosis, were not observed on the histological

examination of the cutaneous biopsy, therefore our

diagnosis was feline phaeohyphomycosis. The small

clusters of brown globose cells visualized on histo-

pathology were interpreted as transverse sections ofpigmented hyphae or pigmented yeast-like cells. How-

ever, they may represent stages of the development of

sclerotic bodies, typical of chromoblastomycosis, in

which the secondary septa had yet to be formed. His-

topathological pictures depicting such cell clusters

formed by F. pedrosoihave been reported in cases of

human chromoblastomycosis.1Moreover, histopatho-

logical human diagnostic criteria to differentiate

phaeohyphomycosis from chromoblastomycosis

have not yet been recognized unanimously in feline

medicine. In fact, sclerotic bodies have been described

in cases of feline phaeohyphomycosis.10

Because of the route of entry of fungal organisms,

which is from contaminated wounds, feline phaeohy-

phomycosis occurs most commonly as a single nodular

lesion, variably ulcerated, on a distal extremity. Inhala-

tion of airborne fungal elements has been hypothesized

to represent the route of infection in cases of dissemin-

ated disease.9In our case, the presenting signs and the

lack of history of nasal skin wounds would have been

compatible with primary respiratory fungal coloniza-

tion. Sneezing may have been due to nasal mucosal

swelling, undetectable on routine films. However, fungal

colonization in our case should have been limited to

the initial respiratory tract, in fact dissemination of theinfection and underlying immunosuppression were not

detected.

However, penetration of fungal elements by wound

contamination could not be ruled out; in fact, as also

in human phaeohyphomycosis, precipitating trauma at

the site is seldom recalled because lesions are often

present for months or years before coming to medical

attention. The insect sting/ bite might have represented

the source of infection. Human chromoblastomycosis

provoked by an insect bite has been reported13 and

F. pedrosoi has been isolated from abandoned wasp

nests.

14

Furthermore, the black dot observed initiallyby the owner on the skin surface might have repres-

ented dried blood from the wasp sting or from other

trauma. It seems unlikely that the black dot might

have represented pigmented fungal elements elim-

inated transepidermally, as described in human chro-

moblastomycosis,15because the nasal swelling was not

clinically evident at that time.

The treatment choice in our case was based on a pre-

vious report of feline granulomatous rhinitis due to

phaeohyphomycosis which was treated successfully with

itraconazole.16In addition, F. pedrosoi, at least in vitro,

has been reported to be susceptible to itraconazole.17

Complete surgical resection of small lesions, with awide surgical margin of healthy tissue, in feline and

human phaeohyphomycosis and in human chromob-

lastomycosis may be curative. However, total cure is

generally not achieved and recurrence is common.

Medical treatment of nonresectable lesions is difficult

and, to date, a treatment of choice has not been found.

Ketoconazole, itraconazole, amphotericin B and flucy-

tosine have been used alternatively with variable results

to treat feline phaeohyphomycosis.9Amphotericin B,

flucytosine, azoles, triazoles, terbinafine and combineddrug regimens, with or without physical treatment,

have been used alternatively over the years to treat both

human phaeohyphomycosis and chromoblastomyco-

sis with variable results.18In our case, medical treat-

ment with itraconazole was able to induce clinical

remission, but relapses occurred twice. This may be due

to insufficient duration of treatment, which in humans

may last up to 3 or 4 years, although treatment was

maintained for 3 and 5 months, respectively, after signs

of the disease disappeared. However, F. pedrosoiis the

causal agent of chromoblastomycosis least susceptible

to antifungal chemotherapy and this might account

for therapeutic failure.11

The use of newer azoles to treat feline dermal and

subcutaneous fungal infections needs further evalu-

ation. In fact, there are few reported cases regarding the

effectiveness of the triazoles for these diseases in cats.9

In humans they seem to achieve clinical cure, singly

or in combination, but the dose and the duration of

therapy appear to be high and prolonged.11

ACKNOWLEDGEMENTS

The authors would like to thank Prof. Claude DeBivre (Institut Pasteur, Paris) for his supervision in the

identification of Fonsecaea pedrosoiand Prof. Luis Ferrer

for the scientific supervision of the manuscript.

REFERENCES

1. Kwon-Chung, K.J., Bennet, J.E. Medical Mycology.

Philadelphia: Lea & Febiger, 1992: 33754.

2. Ajello, L., Georg, L.K., Steigbigel, R.T. et al.A case of

phaeohyphomycosis caused by a new species of Phialo-

phora. Mycologia1974; 66: 4908.

3. Chermette, R., Ferreiro, L., de Bivre, C. et al.Exophialaspiniferanasal infection in a cat and a literature review

of feline phaeohyphomycoses. Journal of Medical

Mycology1997; 7: 14958.



5. Rippon, J.W. Medical Mycology. The Pathogenic Fungi

and the Pathogenic Actinomycetes. Philadelphia: W.B.

Saunders, 1988: 797.

6. McGinnis, M.R., DAmato, R.F., Land, G.A. Handbook

of Medically Important Fungi and Aerobic Actinomycetes.

Praeger Scientific Editions, 1979: 160.

7. Roosje, P.J., de Hoog, G.S., Willemse, T. Phaeohyphomy-

cosis in a cat caused by Alternaria infectoriaE. G. Simmons.Mycoses1993; 36: 4514.

8. Norton Rossmann, S., Cernoch, P.L., Davis, J.R. Dema-

tiaceous fungi are an increasing cause of human disease.

Clinical Infectious Diseases1996; 22: 7380.


5/5


Phaeohyphomycosis in a cat 301

9. Foil, C.S. Miscellaneous fungal infections. In: Greene, C.E.,

ed. Infectious Diseases of the Dog and Cat. Philadelphia:

W.B. Saunders, 1998: 42030.

10. Scott, D.W., Miller, W.H., Griffin, C.E. Muller and Kirks

Small Animal Dermatology. Philadelphia: W.B. Saunders,

1995: 35861.

11. Sharma, N.L., Sharma, R.C., Grover, P.S.et al.Chromob-

lastomycosis in India. International Journal of Dermatology1999; 38: 84651.

12. Odds, F.C., Arai, T., DiSalvo, A.F. et al.Nomenclature

of fungal diseases: a report and recommendations from a

sub-committee of the International Society for Human

and Animal Mycology (ISHAM). Journal of Medical and

Veterinary Mycology1992; 30: 110.

13. Sauerteig, E., Hernndez, R., Salfelder, K. et al.Acute

chromoblastomycosis provoked by an insect bite in an

immunosuppressed patient. Mycoses1998; 41: 1914.



15. Wortman, P.D. Concurrent chromoblastomycosis caused

by Fonsecaea pedrosoi and actinomycetoma caused by

Nocardia brasiliensis. Journal of the American Academy

of Dermatology1995; 32: 3902.

16. Michaud, A.J. Phaeohyphomycosis rhinitis due to

Exophiala jeanselmeiin a domestic cat. Feline Practice1993; 21: 1923.

17. de Bedout, C., Gomez, B.L., Restrepo, A. In vitrosuscept-

ibility testing of Fonsecaea pedrosoi to antifungals.

Revista do Instituto de Medicina Tropical de Sao Paulo

1997; 39: 1458.

18. Esterre, P., Inzan, C.K., Ramarcel, E.R. et al.Treatment

of chromomycosis with terbinafine: preliminary results

of an open pilot study. British Journal of Dermatology

1996; 134(Suppl. 46): 33 6.

Rsum Cet article prsente le premier cas de phaeohyphomycose fline d Fonsecaea pedrosoi. Fonsecaea

pedrosoiest responsable chez lhomme de phaeohyphomycose et de chromoblastomycose. Pour notre animal, lalsion tait limite la peau sous la forme dun paississement ferme du chanfrein. Le diagnostic a t ralis

par lexamen histopathologique dune biopsie cutane et par culture fongique sur milieu de Sabouraud. Des tests

supplmentaires nont pas permis de rvler dimmunodficit chez cet animal. Deux cures ditraconazole la dose

de 5 mg kg1deux fois par jour per os ont permis une gurison complte, mais des rcidives sont apparues.

[Fondati, A., Grazia Gallo, M., Romano, E., Fondevila, D. A case of feline phaeohyphomycosis due to Fonsecaea

pedrosoi. (Un cas de phaeohyphomycose due Fonsecaea pedrosoichez un chat.) Veterinary Dermatology12:

297301.]

Resumen Se presenta el primer caso clnico de feohifomicosis felina debida a Fonsecaea pedrosoi. Fonsecaea

pedrosoies un agente etiolgico tanto en la feohifomicosis felina como en la cromoblastomicosis. En nuestro gato,

la lesin se encontraba confinada a la piel y apareca como una tumefaccin dura en el puente nasal. El diagnstico

se bas en el estudio histolgico de biopsias cutneas y en el cultivo fngico de una muestra de biopsia en agar

dextrosa Sabouraud. Otras pruebas llevadas a cabo no mostraron una inmunosupresin subyacente. Dos ciclosde tratamiento con itraconazole, con una dosis de 5 mg kg1administrada dos veces al da, llevaron a una remisin

clnica completa, aunque se produjeron recidivas. [Fondati, A., Grazia Gallo, M., Romano, E., Fondevila, D.

A case of feline phaeohyphomycosis due toFonsecaea pedrosoi. (Un caso de feohifomicosis felina debida a

Fonsecaea pedrosoi.) Veterinary Dermatology12: 297 301.]

Zusammenfassung Der erste Fallbericht von feliner Phohyphomykose verursacht durch Fonsecaea pedrosoi

wird vorgestellt. Fonsecaea pedrosoiist ein tiologisches Agens von humaner Phohyphomykose und Chromob-

lastomykose. Bei dieser Katze war die Lsion auf die Haut beschrnkt und erschien als feste Schwellung auf dem

Nasenrcken. Die Diagnose basierte auf der histologischen Untersuchung einer Hautbiopsie und der Pilzkultur

einer Gewebsprobe auf Sabourauds Dextroseagar. Weitere diagnostische Untersuchungen konnten keine

Immunsuppression nachweisen. Zwei Behandlungszyklen mit Itrakonazol in einer Dosierung von 5 mg kg1

zweimal tglich fhrten zur kompletten klinischen Remission, aber Rezidive traten auf. [Fondati, A., Grazia Gallo, M.,

Romano, E., Fondevila, D. A case of feline phaeohyphomycosis due to Fonsecaea pedrosoi. (Ein Fall von feliner

Phohyphomycose verursacht durch Fonsecaea pedrosoi.) Veterinary Dermatology12: 297 301.]

a case of feline phaeohyphomycosis due to fonsecaea pedrosoi (pages 297–301)

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