Chromoblastomycosis

Overview

Chromoblastomycosis is a long-lasting fungal infection of the skin and the tissue just beneath it. It is caused by several types of dark-pigmented fungi that live in soil, wood, and decaying plant material. The fungi enter the body through a small cut, splinter, or thorn prick, usually on the legs or feet, and then slowly grow over many months to years.

Over time the infection produces raised, warty, scaly skin lesions that can resemble cauliflower-like growths. It is most common in tropical and subtropical regions and tends to affect people who work outdoors, such as farmers and laborers. The infection progresses slowly and can be difficult to treat, but it is not usually life threatening and does not spread from person to person.

Symptoms

Symptoms develop gradually over years and are usually limited to the skin and nearby tissue. They include:

• A small bump or scaly patch at the site of a skin injury that slowly enlarges.
• Raised, warty, cauliflower-like growths over time.
• Thickened, scaly, or crusted skin patches.
• Itching in the affected area.
• Spread to nearby skin as new lesions appear around the original one.
• Complications such as added bacterial infection, ulceration, swelling from blocked lymph flow, and, rarely, changes in long-standing lesions.

Causes

Chromoblastomycosis is caused by a group of dark-walled fungi found in the environment, particularly in soil, wood, and rotting vegetation. People become infected when these fungi are pushed into the skin through a minor injury, such as a thorn prick, splinter, or scratch.

Because the injury often happens during outdoor work and frequently affects bare or exposed skin, the legs and feet are most commonly involved. The infection stays localized to the skin and tissue beneath it and is not passed from one person to another.

Risk Factors

• Living or working in tropical or subtropical regions
• Outdoor work involving soil, wood, or plants, such as farming
• Walking barefoot or with minimal foot protection
• Frequent minor skin injuries from thorns or splinters
• Being an adult, especially male, the group most often affected

Diagnosis

Diagnosis relies on identifying the fungus in skin samples.

• Skin scraping or biopsy: Examined under a microscope, where the fungi appear as characteristic dark, rounded structures.
• Fungal culture: To grow and identify the specific fungus, which can guide treatment.
• Clinical assessment: Considering the warty appearance, location, and history of outdoor exposure or skin injury.

Because the lesions can resemble other skin conditions and infections, laboratory confirmation is important.

Treatment

Chromoblastomycosis can be difficult to cure, especially when lesions are large or long-standing. Treatment is usually prolonged and may combine several approaches:

• Antifungal medication: Long-term oral antifungal drugs are the mainstay of treatment.
• Physical therapies: Such as freezing the lesions (cryotherapy) or heat therapy, sometimes used alongside medication for smaller lesions.
• Surgery: Removal of small, well-defined lesions may be possible.
• Treating complications: Such as added bacterial infection or swelling.

Treatment success depends heavily on how early the infection is caught, since small, recent lesions are easier to treat than large, long-standing ones. Combining antifungal medicine with physical therapies sometimes works better than either alone. Because relapse is common, treatment often continues for many months even after the skin looks better, and close follow-up is needed to confirm the infection is truly gone.

Prevention

There is no vaccine. Prevention centers on avoiding skin injuries that let soil fungi enter:

• Wear shoes and protective footwear when working outdoors
• Use gloves and protective clothing when handling soil, wood, or plants
• Clean and cover cuts, splinters, and thorn pricks promptly
• Seek care early for a slow-growing skin lesion that does not heal

When to See a Doctor

See a doctor if you have a slowly growing, warty, or scaly skin lesion that does not heal, especially on the legs or feet after a skin injury or outdoor work. Seek prompt care if you notice:

• Increasing pain, redness, warmth, pus, or fever, suggesting added bacterial infection
• Significant swelling of the limb
• Rapid change in a long-standing lesion
• Spreading lesions or open sores

Related Topics

Frequently Asked Questions

References

1. Centers for Disease Control and Prevention (CDC). Chromoblastomycosis.
2. World Health Organization (WHO). Chromoblastomycosis and other deep mycoses.
3. MedlinePlus, U.S. National Library of Medicine.
4. StatPearls, National Library of Medicine. Chromoblastomycosis.