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Skin-nontumor / Clinical Dermatology

Infectious disorders

Fungi - Chromoblastomycosis


Reviewer: Ha Kirsten Do, M.D., IUPUI (see Reviewers page)
Revised: 14 November 2010, last major update September 2010
Copyright: (c) 2002-2010, PathologyOutlines.com, Inc.

Definition
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● Chronic deep cutaneous fungal infection usually affecting the limbs at the inoculation site

Causative agents include several fungi found in soil, wood and decaying plant material:
Phialophora verrucosa
● Fonsecaea pedrosi
(most common pathogen, accounts for > 90% of the cases in South America)
Fonsecaea compacta
● Cladosporium carrionii
● Rhinocladiella aquaspersa (Ramichloridium cerophilum)


Epidemiology
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● First case of chromoblastomycosis was reported by Pedroso in Brazil in 1911
● Incidence of chromoblastomycosis is greatest in tropical and subtropical regions, including Madagascar, Brazil, Gabon, Colombia, Venezuela, Cuba, the Dominican Republic and Mexico
● Up to 70% of cases occur in males
● Barefooted farmers account for almost 75% of patients with chromoblastomycosis

Clinical features
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● Common clinical presentation is verrucous lesion over extremities of adult men engaged in outdoor work (Indian J Pathol Microbiol 2010;53:666)
● The disease is slowly progressive - the average time between the initial lesion and the clinical diagnosis is 15 years
● Lesion starts as a small firm red/grey bump on the traumatized skin on the foot or hand
● Grows slowly (2mm/year) to form raised hyperkeratotic (crusted, warty-looking) plaque
● The affected limp can be enlarged (elephantiasis)
● Can develop satellites lesions (new lesions near primary lesion)
● Rarely, squamous cell carcinoma develops within longstanding chromoblastomycosis (An Bras Dermatol 2010;85:267)
Diagnosis: culture at 25-30 degrees Celsius grows olive-green to black fungal colonies after 1-2 weeks

Treatment
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● Treatment is difficult and long
● A Mexican study showed 30% cure rate, 60% improvement, and 10% failed therapy
● Smaller lesions are best treated with surgical excision or cryotherapy (multiple treatments may span up to 10 years)
● Extensive lesions can be treated with itraconazole (up to several years), or terbinafine (up to several months)
● Often dramatic improvement at first, but difficult to cure
● Some studies suggest a multidrug approach is more effective: itraconazole + flucytosine; flucytosine + amphotericin B
● Recalcitrant lesions can be treated with a combination of itraconazole and cryotherapy or local hyperthermia or CO2 laser vaporization

Clinical images
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Hyperkeratotic plaque

Chronic verrucous chromoblastomycosis of hand due to Cladophialophora carrionii

   

Cultures are typically olive-black with a suede-like surface

Micro description
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● Clinical suspicious is important to alert pathologists to check for sclerotic bodies, which may be rare
● The classical histopathological hallmarks are pseudoepitheliomatous hyperplasia with intraepidermal abscess and pigmented fungal sclerotic bodies (Medlar bodies or “copper bodies”)
● Fungi appear in clusters that reproduce by equatorial septation rather than budding
● Fungal stains show fungi within macrophages and rarely in factor XIIIa-positive dedrocytes or Langerhan cells

Micro images
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Sclerotic bodies: H&E and KOH prep

Micromorphology of Cladosporium carrionii (left) and Fonsecaea pedrosoi (right), the 2 most common pathogenic fungi causing chromoblastomycosis

   

H&E stain of sclerotic bodies in an intraepidermal abscess


Hyperkeratosis, pseudoepitheliomatous hyperplasia, chronic inflammatory infiltrate and micro-abscess

Differential diagnosis
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● Leishmaniasis
● Sporotrichosis
● Squamous Cell Carcinoma

Additional references
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J Am Acad Dermatol 1991;25:869, Wikipedia, eMedicine

End of Skin-nontumor / Clinical Dermatology > Infectious disorders > Fungi - Chromoblastomycosis


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