Phaeohyphomycosis and Chromomycosis
(Chromoblastomycosis; Verrucous Dermatitis; Hematomycosis)

Infections of subcutaneous tissues, sinuses, brain, and other tissues caused by dark, melanin-pigmented dematiaceous fungi (including species of Bipolaris, Cladophialophora, Cladosporium, Drechslera, Exophiala, Fonsecaea, Phialophora, Xylohypha, Ochroconis, Rhinocladiella, Scolecobasidium, and Wangiella).

Symptoms and Signs

Chromomycosis is a cutaneous infection affecting normal, immunocompetent persons mostly in tropical or subtropical areas, characterized by formation of papillomatous nodules that tend to ulcerate. Most infections begin on the foot or leg, but other exposed body parts may be infected, especially where the skin is broken. Early small, itchy, enlarging papules may resemble dermatophytosis (ringworm). These extend to form dull red or violaceous, sharply demarcated patches with indurated bases. Several weeks or months later, new lesions, projecting 1 to 2 mm above the skin, may appear along paths of lymphatic drainage. Hard, dull red or grayish cauliflower-shaped nodular projections may develop in the center of patches, gradually extending to cover extremities over periods as long as 4 to 15 years. Lymphatic obstruction may occur, itching may persist, and secondary bacterial superinfections may cause ulcerations and, occasionally, septicemia.

Dematiaceous fungi also may cause other patterns of infection in normal hosts and have been increasingly recognized as opportunists affecting immunocompromised patients. Most mycology texts distinguish these extracutaneous infections as phaeohyphomycosis. Invasive sinusitis, sometimes with bony necrosis, as well as subcutaneous nodules or abscesses, keratitis, lung masses, osteomyelitis, mycotic arthritis, intramuscular abscess, endocarditis, brain abscess, or chronic meningitis, may occur.

Diagnosis, Prognosis, and Treatment

Late chromomycosis lesions have a characteristic appearance, but early involvement may be mistaken for dermatophytoses. Phaeohyphomycosis must be distinguished by histopathology and culture from the myriad other causes of facial extracutaneous infectious and noninfectious conditions. Dematiaceous fungi are frequently discernible in tissue specimens stained with conventional hematoxylin and eosin, appearing as septate, brownish bodies reflecting their natural melanin content. Masson-Fontana staining for melanin confirms their presence. Culture is needed to identify the causative species.

Dematiaceous fungi only rarely cause fatal infections in those who have normally intact host defense mechanisms; life-threatening illnesses occur more often in immunocompromised patients. Itraconazole is the most effective antifungal drug, although not all patients respond. Flucytosine is sometimes useful for ancillary therapy, because some lesions may respond rapidly but generally relapse. Fluconazole seldom causes lesions to regress, and amphotericin B is ineffective. Many cases require surgical excision for cure.

Source: Merck Manual