An unusual case of onychomycosis due to
Fonsecaea pedrosoi
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Case Report
An unusual case of onychomycosis due toFonsecaea pedrosoi
B. Shweta a,*, A. Archana b, G. Nupur a
a Specialist, Microbiologist, National Centre for Disease Control, 22, Sham Nath Marg, Delhi 110054, Indiab Public Health Specialist, National Centre for Disease Control, 22, Sham Nath Marg, Delhi 110054, India
a r t i c l e i n f o
Article history:
Received 7 November 2014
Accepted 7 November 2014
Available online xxx
Keywords:
Onychomycosis
Dematiaceous
Fonsecaea pedrosoi
* Corresponding author.E-mail address: [email protected] (B.
Please cite this article in press as: Shweta(2014), http://dx.doi.org/10.1016/j.apme.2
http://dx.doi.org/10.1016/j.apme.2014.11.0030976-0016/Copyright © 2014, Indraprastha M
a b s t r a c t
Onychomycosis is usually caused by dermatophytes, but some nondermatophytic molds
and yeasts are also associated with invasion of nails. Here is a report of a case of distal and
lateral subungual onychomycosis (DLSO) caused by Fonsecaea pedrosoi where it acts as
primary agent of nail infection.
Case report: A 30-year-old male presented with a 1-year history of brownish-black discol-
oration with hyperkeratosis on the finger and toenails. Scrapings were collected for smears
and culture.
Dematiaceous hyphae were seen on wet mounts of the scrapings and dark pigmented
colonies grew repetitively on the culture media; all colonies were identical, and were
subsequently identified as F. pedrosoi.
In humid tropical regions F. pedrosoi is one of the primary causes of human chronic
cutaneous mycosis, chromoblastomycosis. The case presented had certain unusual fea-
tures. The disease was caused by an unusual fungus (Fonsecaea), occurred at an unusual
site (nail) and in an immunocompetent individual.
Combination of antifungal medications may provide the best option for cure in
onychomycosis.
Copyright © 2014, Indraprastha Medical Corporation Ltd. All rights reserved.
1. Introduction
Onychomycoses constitutes a frequent fungal infections seen
in dermatological practice worldwide. The clinical picture is
very variable, but that in general is characterized by nail ar-
chitecture alterations, such as changes in color, thickness,
onycholysis and onycodistrophy. In most cases they are
caused by species of filamentous fungi like the dermatophytes
or yeasts of the genus Candida. However, in a small fraction of
the cases, the etiologic agents comprise nondermatophyte
filamentous fungi, belong to several genera and species.1
Shweta).
B, et al., An unusual cas014.11.003
edical Corporation Ltd. A
Nondermatophyte onychomycosis account for 2%e12%
of all nail fungal infections and can be caused by a wide
range of fungi, including Scopulariopsis brevicaulis,
Penicillium spp., Aspergillus spp., Fusarium spp., Ulocla-
dium spp., Acremonium spp., Alternaria spp, Cladosporium
spp., Paecilomyces spp., Curvularia spp., Chaetomium
spp.,Scytalidium spp and Trichoderma spp.2e5 The preva-
lence of nondermatophyte onychomycosis varies widely,
according to geographical location or the climate, but it is
more frequent in hot and humid tropical areas. Often they
are considered simple contaminants or secondary patho-
gens, invading nails previously damaged by trauma or
e of onychomycosis due to Fonsecaea pedrosoi, Apollo Medicine
ll rights reserved.
a p o l l o m e d i c i n e x x x ( 2 0 1 4 ) 1e32
disease, although in some cases they actually act as primary
pathogens.1
Dematiceous fungi are the etiological agents of phaeohy-
phomycosis and are now increasingly being recognized as
causing disease in humans specially in immunocompromised
patients.6 Fonsecaea pedrosoi, a dematiceous fungi, is the
commonest causative agent of chromoblastomycosis a
chronic mycotic cutaneous and subcutaneous skin infection,
which primarily occurs in humid tropical regions.7 Till now
only one case of nail infection i.e. of longitudinal melano-
nychia secondary to chromoblastomycosis due to F. pedrosoi
has been reported.8
Here, we report a case of distal and lateral subungual ony-
chomycosis (DLSO) caused by F. pedrosoi where it acts as pri-
mary agent of nail infection. The objective of this study was to
present a case of onychomycosis associated to thedematiceous
fungi F. pedrosoi in a reference hospital in new Delhi, India.
Aspects of fungal pathogenesis, as well as the epidemio-
logical characteristics and laboratory diagnosis, are discussed
below.
2. Case report
A 30-year-old male presented with a 1-year history of
brownish-black discolorationwith hyperkeratosis on the finger
and toenails. There was no history of other symptoms except
for finger and toenail dystrophy. Dermatological examination
revealed theDLSOon the right fingernails (1st and 5th), toenails
(1st, 2nd, 4th and 5th) and left toenails (1st and 5th). Complete
blood count, peripheral blood smear, urinalysis, liver and renal
function tests and stool examination were within normal
limits for both patients. Venereal disease research laboratory
test and serological tests for hepatitis virus and human im-
munodeficiency virus were also negative. Chest X-ray and
electrocardiogram were unremarkable. In mycological exami-
nation, fungal elementswere observed in potassiumhydroxide
(KOH) preparations from the both toenail and fingernail lesions
of the patient. Nail specimens were cultured on two slants of
Sabouraud's dextrose agar (SDA) without cycloheximide at
25 �C for 2 weeks, which yielded several identical appearing
colonies. The moderately slow-growing colonies were initially
white then turned spreading, lanose and olivaceous-green
colonies with a blackish reverse. We performed repeated
(three) cultures taken from nail plates at 2-week intervals; all
yielded similar findings. When the slide cultures of fungal
colonies were stained with lactophenol cotton blue, it showed
the two typical morphologic forms: i) light brown co-
nidiophores, profusely branched with cylindrical, intercalary
or terminal conidiogenous cells with clusters of prominent
denticles and ii) the Phialophora synanamorph, characterized by
ampulliform, darker phialides with conspicuous funnel-
shaped collarettes. The conidia were smooth-walled, clavate,
pale olivaceous and measured 3.5e5 � 1.5e2 mm.
3. Discussion
Dematiaceous fungi, including F. pedrosoi, are a group of het-
erogeneous ubiquitous fungi known to cause
Please cite this article in press as: Shweta B, et al., An unusual cas(2014), http://dx.doi.org/10.1016/j.apme.2014.11.003
phaeohyphomycosis, a spectrum of disease ranging from su-
perficial to deep-seated infections.6 The distinguishing char-
acteristic common to these fungi is the presence ofmelanin in
their cell wall, which is also believed to be a virulence factor.6
The genus Fonsecaea is not an established cause of ony-
chomycosis. To the best of the present authors' knowledge,
only one case of longitudinal melanonychia secondary to
chromoblastomycosis due to F. pedrosoi has been reported.8
However no case where F. pedrosoi acts as a primary cause of
onychomycosis has been reported till date. Infection is
through traumatic inoculation into the skin with infected
plant material. These infections can be classified in four
clinical forms: superficial, cutaneous, subcutaneous and sys-
temic. In category cutaneous includes the onychomycosis.9
Onychomycosis caused by dematiceous fungi is unusual.
These organisms are characterized by brownish-black
pigmentation of the host cells and culture of their colonies
blackish brown. So, due to this natural pigmentation of their
septate hyphae, can simulate melanonychia caused by mel-
anocytic lesions such as melanoma of the nail apparatus.9
From the clinical view point, the lesions caused by infect-
ing species of the genus Fonsecaea were very similar to those
caused by dermatophytes. The affected nails displayed dis-
trophy and onycholysis, usually with alterations of the distal
subungueal region.10
Regarding the laboratory diagnosis of Fonsecaea infections,
as in other nondermatophyte fungi infections, it is always
necessary to confirm if the fungus is the real etiologic agent of
the onychomycosis, by the repetition of the examswith a new
collected sample.10
The case presented had certain unusual features. The
disease was caused by an unusual fungus (Fonseca0e00 a),
occurred at an unusual site (nail) and in an immunocompe-
tent individual.
Treatment of the mycosis caused by this agent is unre-
warding not only because of the scarcity of effective anti-
fungals but also due to the need for prolonged periods of
treatment, which in some reports has required prolonged
therapeutic regimens of up to 2 years to obtain a mycologic
cure. Several studies have indicated, by minimal inhibitory
concentration (MIC)values, that itraconazole presents no
resistance to F. pedrosoi.7 Although in vitro susceptibility
testing does not reliably predict in vivo efficacy for fungi, and
MICs can not be used as strict guidelines for therapy, the
possibility of performing in vitro tests should be considered.
In that way, one may avoid ineffective, costly and a pro-
longed course of treatment. In view of the lack of suscepti-
bility of this agent to the current antimycotic drugs, it may
be wiser to seriously consider the possibility of combining
the best available drugs in order to obtain a synergistic
effect.7
Therefore, a high index of suspicion in both treating clini-
cians andmicrobiologists is necessary for the diagnosis of this
entity, the reasons being the rarity of the disorder and the
need for prolonged treatment, once identified. Confirmation
of the specific pathogen (such as F. pedrosoi, in this case) would
lead to not only initiation of the proper therapy but also pre-
vention of premature discontinuation of therapy that would
potentially deny the benefit of getting cured to the rare patient
who may be unfortunate enough to suffer from this disease.
e of onychomycosis due to Fonsecaea pedrosoi, ApolloMedicine
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Other importance of this case is the differential diagnosis
of cause of melanonychia, especially with melanomas of the
nail apparatus, as this rare type of cancer has bleak prognosis.
In conclusion, clinicians must appreciate that the Non-
dermatophyte fungi should no longer be disregarded as pure
contaminants and choose optimal antifungal agents
accordingly.
Conflicts of interest
All authors have none to declare.
r e f e r e n c e s
1. Rell LN, Hasse J, Galindo CC, et al. Onychomycosis byScytalidium dimidiatum: report of two cases in SantaCatarina, Brazil. Rev Int Med Trop. 2005;47:351e353.
2. Naidu J. Growing incidence of cutaneous and ungulainfections by non-dermatophyte fungi at Jabalpur(M.P.).Indian J Pathol Microbiol. 1993;36:113e118.
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3. Hilmioglu-Polat S, Metin DY, Inci R, et al. Non-dermatophytic molds as agents of onychomycosis inIzmir, Turkey e a prospective study. Mycopathologia.2005;160:125e128.
4. King DM, Lee MK, Suh MK, et al. Onychomycosis caused byChaetomium globusum. Ann Dermatol. 2013;25:232e236.
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6. Singh N, Agarwal R, Gupta D, et al. An unusual case ofmediastinal mass due to Fonsecaea pedrosoi. Eur Respir J.2006;28:662e664.
7. Lima ALH, Guarro J, Freitad D, et al. Clinical treatment ofcorneal infections due to Fonsecaea pedrosoi e case Report.Arq Bras Oftalmol. 2005;68:270e272.
8. Sarti HM, Vege-Memije ME, Dominguez-Cherit, et al.Longitudnal melanonychia secondary tochromoblastomycosis due to Fonsecaea pedrosoi. Int JDermatol. 2008;47:764e765.
9. Carvalho Vl, Mendonca IM, Val A, et al. Melanonychia : thepurpose of a case simulating. Dermatol Online J. 2010;16.
10. Gupta AK, Ryder JE, Summerbell RC. The diagnosis ofnondermatophyte mold onychomycosis. Int J Dermatol.2003;42:272e273, 2.
e of onychomycosis due to Fonsecaea pedrosoi, Apollo Medicine
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