Treating Rare Fungal Infections: Chromoblastomycosis

First identified in the early 1910s, chromoblastomycosis—otherwise known as chromomycosis—is a subcutaneous dematiaceous fungal infection. It is slow-to-develop and chronic, associated with poor treatment outcomes and persistent relapse rates, but is not considered fatal. Once referred to as a disease of rural workers, chromoblastomycosis is now presenting in people working in various other sectors. 

Chromoblastomycosis presenting on the toes, foot and ankle. Source: Graham Library of Digital Images, Wake Forest University Department of Dermatology © 2009 Wake Forest University Dermatology

Epidemiology and Pathogensis

Chromobastomycosis results from skin inoculation by pigmented fungi including Fonsecaea pedrosoi, Phialophora verrucosa, Cladophialophora carrionii, Fonsecaea compacta and Wangiella dermatitis.¹ F. pedrosoi and C. carrionii are the most common causes.² Most pigmented fungi are found in environments that contain wood, plant debris or soil. These mycoses are usually isolated in subtropical and tropical climages, particularly Central and South America, Japan and Australia.³

Clinical Presentation

The saprophytic fungi implant into the skin following traumatic injury, particularly in areas that are not covered by clothing or shoes.⁴ The initial site of infection is usually on the arms, upper trunk, legs or feet, although unusual sites of infection in the genitalia and nose have been reported.^3,5 The clinical presentation of the lesions include 5 distinct appearances: nodular lesions with raised surfaces that are covered by cauliflower-like scabs; extensive tumoral lesions; extensive, irregular verrucose, hyperkeratotic lesions; reddish, flat, scaly plaques; and cicatricial atropic skin lesions with sparing at the center.^2-4

Diagnostic Testing

Lesion scrapings must be examined under a microscope in KOH stain (10% potassium hydroxide). Medlar bodies, muriform bodies or scleratoic cells will be visible with the potassium hydroxide stain as round, brown, thick-walled and multi-septate cells.⁵

For more information about chromoblastomycosis, including treatment protocols, please read the complete article in The Dermatologist.

References
1. Esterre P. Chromoblastomycosis. In: WG Merz, RJ Hay, ed. Topley and Wilson’s Microbiology and Microbial Infections: Medical Mycology. London: Hodder Arnold; 2004: 356.
2. López MR, Tovar M. Chromoblastomycosis. Clin Exp Dermatol. 2007;25(2):188-194.
3. Correia RT, Valente NY, Criado PR, Martins JE. Chromoblastomycosis: Study of 27 cases and review of medical literature. An Bras Dermatol. 2010;85(4):448-54.
4. Goette DK, Robertson D. Transepithelial elimination in chromomycosis. Arch Dermatol.1984;120(3):400-401.
5. Ameen M. Chromoblastomycosis: Clinical presentation and management. Clin Exper Dermatol. 2009;34(8):849-854.