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Fig. 6.30. Visceral entomophthoromycosis may present clinically with abdominal symptoms. Although not common, the large bowel may be so involved as to cause obstruction, as shown in this specimen from Brazil. The infection can spread throughout the abdomen, causing hydronephrosis in some patients. (From Bittencourt and Londero 1995, and Dr. Rui Moreira, Salvador)

Fig.6.31. Chromoblastomycosis can resemble squamous cell carcinoma. Histopathologically there is a heavy cellular reaction, with inflammatory cells mixed with epitheloid and giant cells. Microabscesses of neutrophils occur in the center of these granulomas (arrow). H & E, x200. (From Bittencourt and Londero 1995)

Fig. 6.32. A Chromoblastomycosis on the right leg, mimicking squamous cell carcinoma. B, C Radiography shows marked soft tissue swelling of the foot with irregular nodules of different sizes. The infection is confined to the soft tissues and does not involve bone, cause displacement or affect the joints. However, very rarely, this fungus can cause chronic osteomyelitis.


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Chromoblastomycosis and Phaeohyphomycosis

Previously known as chromomycosis, this is another mycotic infection for which the nomenclature has changed since the first (1981) edition and is still very confusing. To quote "Medical Mycology" again (K. J. Kwon-Chung and J. E. Bennett, 1992), the "nomenclature of many phaeohyphomycotic agents has been complex because of confusion in their classification ... and the different opinions of taxonomists."

This group of infections is described because the fungi have been reported from every continent, with the majority of the patients coming from the rural tropics and subtropics. It is the complications in patients with unusual spread of the fungus which are of importance in imaging. The initial lesions have no specific imaging characteristics.


Chromomycosis. Verrucous dermatitis. Phaeosporotrichosis. (There are numerous other older names.)
Phaeomycotic cyst. This is different clinically and pathologically, and different because it is easily cured by excision. There are no imaging features and it is not discussed further.
Fr: Chromoblastomycose. Ger: Chromomykose. Chromoblastomykose. Sp: Cromoblastomicosis.


A chronic infection of the skin and subcutaneous tissue caused by one of the naturally pigmented fungi. Most infections are caused by Fonsecaea pedrosoi. The definition is based around the clinical characteristics, which are common to many of these fungal infections, and phaeohyphomycosis is the supporting histopathological definition. Unfortunately, the names chromomycosis and chromoblastomycosis are used differently in different texts, referring to different fungi. There are organisms which can cause both chromoblastomycosis and phaeohyphomycosis, and previously these were included under chromoblastomycosis. Now mycologists are trying to separate the clinical conditions in chromoblastomycosis from those of phaeohyphomycosis.

Geographic Distribution

Chromoblastomycosis is most common throughout the tropics but may be found anywhere in the world except in the Arctic and Antarctic. There are some areas where the infection is highly endemic, such as the Dominican Republic, Costa Rica, and, in Africa, the Malagasy Republic. In many arid regions, the infection is rare. There is also geographic variation between the causal species.

Epidemiology and Pathology

The organisms are saprophytes found in decaying vegetable matter, on woody plants, and in the soil. The common characteristics of the wide group of fungi which can cause clinical chromoblastomycosis are that they are pigmented (brown, from melanin), muriform, and yeast-like with hyphae which divide by septation (binary fission) and not by budding. They are introduced into tissues by trauma (e. g., with thorns or splinters): transmission from person to person does not occur. The histopathological pattern lies between an infected (suppurative) granuloma and a pseudoepithelioma. There will be many microabscesses in the dermis, a rich infiltrate of eosinophils, many epitheloid cells and giant cells, lymphocytes, and plasma cells. Truly spectacular is the epithelial hyperplasia which frequently resembles squamous cell carcinoma (Fig. 6.31). Fungal elements may be seen in the verrucous lesions, particularly when the skin lesions are flat. Amongst the causal fungi are species of Fonsecaea, Phialophora verrucosa, and Cladosporium (Cladophialophora) carrionii. All may be seen as groups of thick-walled dark brown "sclerotic cells;' either round or angular in shape. Exophiala dermatitidis (formerly Wangiella dermatitidis) has been included as a further cause of chromoblastomycosis, but does not produce these brown sclerotic "muriform" cells usually found in true chromoblastornycosis.


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