Chromoblastomycosis

Chromoblastomycosis is a long-term fungal infection of the skin and subcutaneous tissue (a chronic subcutaneous mycosis). The infection occurs most commonly in tropical or subtropical climates, often in rural areas. It can be caused by many different type of fungi which become implanted under the skin, often by thorns or splinters. Chromoblastomycosis spreads very slowly; it is rarely fatal and usually has a good prognosis, but it can be very difficult to cure. There are several treatment options, including medication and surgery.

Forms of the disease:

* cicatricial
* nodular
* plaque
* tumorous
* verrucous

Histopathology:
The skin lesions show a hyperkeratous pseudoepitheliomatous hyperplasia and keratolytic microabscesses in the epidermis. Dematiaceous hyphae and sclerotic bodies are found in the stratum corneum, with essentially only sclerotic bodies found in the areas of dermal inflammation. The sclerotic bodies are round, thick-walled, muriform, chestnut brown, and 5-12 µm in diameter. Brain abscesses are typically multilocular and well demarcated with thick walls. Irregular dematiaceous hyphae are seen in these abscesses.

Diagnosis:
The most informative test is to scrape the lesion and add potassium hydroxide (KOH), then examine under a microscope. (KOH scrapings are commonly used to examine fungal infections.) The pathognomonic finding is observing Medlar bodies, sclerotic cells. Scrapings from the lesion can also be cultured to identify the organism involved. Blood tests and imaging studies are not commonly used.

Treatment:
Chromoblastomycosis is very difficult to cure. There are two primary treatments of choice. Itraconazole, an antifungal azole, is given orally, with or without flucytosine (5-FC). Alternatively, cryosurgery with liquid nitrogen has also been shown to be effective. Other treatment options are the antifungal drug terbinafine, an experimental drug posaconazole (noxafil), and heat therapy. Antibiotics may be used to treat bacterial superinfections.