Answer to May 2016 Photo Quiz

Answer: Chromoblastomycosis. The melanized elements shown in the photo quiz are muriform cells that can be considered the hallmark of chromoblastomycosis. These fungal structures, which divide by internal septation and are sometimes referred to as “sclerotic” or “fumagoid” cells, “copper pennies,” or “medlar bodies,” were first described in 1915 (1). Muriform cells can be easily visualized after preparation of skin scrapings with potassium hydroxide or, as with our patient, within granulomas along with giant cells after histopathological examination of a skin biopsy specimen. Clinicians, microbiologists, and histopathologists should therefore be aware that the recovery of these structures in clinical specimens allows for diagnosis of chromoblastomycosis and should prompt initiation of therapy. A few days after these cells were identified in our patient, mycological cultures on Sabouraud's dextrose agar grew a dematiaceous fungus identified as a Fonsecaea species (2). Definitive identification of Fonsecaea monophora was eventually obtained by sequencing of the internal transcribed spacer (ITS) region of ribosomal DNA (rDNA). Once the diagnosis was made, two stages of liquid nitrogen cryotherapy were applied. In the absence of significant clinical improvement, the patient was finally switched to oral voriconazole (200 mg twice a day). In March 2013, after 3 months of voriconazole therapy, a significant regression of the lesion was noted and the control biopsy specimen was negative on both direct examination and mycological culture.

Chromoblastomycosis is a chronic and slowly evolving infection of the skin and subcutaneous tissues caused by accidental inoculation of various melanized fungi, the initial trauma being frequently unnoticed or not remembered by the patient. Currently, most cases of chromoblastomycosis are due to Fonsecaea spp., Cladophialophora carrionii, or Phialophora verrucosa (3). Once the fungus is embedded in tissue, the infection may progress slowly over many years or decades. Extension of the infection typically occurs by contiguity and/or autoinoculation, dissemination being infrequent. The disease is diagnosed mostly in male patients in rural areas and typically affects the lower limbs. In addition to the well-known hyperkeratotic and verrucous forms, patients can present with other types of lesions: nodular, tumorous, plaque, pseudovacuole, cicatricial, and eczematous (3). As a consequence, there are a large number of differential diagnoses, including lobomycosis, sporotrichosis, leishmaniasis, verrucose tuberculosis, and squamous cell carcinoma (4). Chromoblastomycosis is a neglected disease occurring mostly in tropical and subtropical climates, with the highest prevalences being observed in Africa (especially Madagascar and South Africa), Latin America (Mexico, Central America, Brazil, and Venezuela), and Asia (India, China, and Malaysia), although the disease has been described as an autochthonous disease in nontropical areas, as illustrated recently in some European countries (3–5).

Therapy is challenging due to low cure rates and frequent relapses (6). Surgical excision is probably the best way to cure chromoblastomycosis but is limited to the early stages of the disease. Clinical data on treatment with itraconazole and terbinafine, alone or combined with physical approaches such as local liquid nitrogen cryotherapy, have been accumulated (6). Voriconazole, posaconazole, or isavuconazole should also be considered promising candidates for treatment of chromoblastomycosis (7).

In conclusion, clinicians and microbiologists should be aware that simple skin scrapings or biopsy specimens of cutaneous lesions evidencing muriform cells can lead to rapid and prompt diagnosis, allowing for initiation of appropriate therapy.

(See page 1179 in this issue [doi:10.1128/JCM.01248-14] for photo quiz case presentation.)