Sporotrichosis

Definition

Sporotrichosis is a long-term (chronic) skin infection due to a certain fungus.

Causes, incidence, and risk factors

Sporotrichosis is caused by the fungus Sporothrix schenckii, which is found in vegetation. Infection commonly occurs when the skin is broken while handling plant materials such as rosebushes, briars, or mulch-rich dirt.

Sporotrichosis can be an occupational disease (for farmers, horticulturists, rose gardeners, plant nursery workers). Widespread (disseminated) sporotrichosis can develop in immunocompromised people when they inhale spore-laden dust.

Symptoms

Symptoms include a small, painless, red lump that develops at the site of infection and eventually turns into an ulcer. The lump may develop up to 3 months following an injury.

Lesions are often on the hands and forearm, as these areas are a common site of injury.

The fungus follows lymph nodes in the body, causing small ulcers to appear in lines on the skin as the infection goes up an arm or leg. These lesions do not heal unless treated and may remain ulcerated for years.

Body-wide (systemic) sporotrichosis can cause lung and breathing problems, bone infection, arthritis, and infection of the nervous system.

Signs and tests

A physical examination reveals the typical lesions. In some cases, a small sample of affected tissue is taken from the body and examined under a microscope to identify the fungus.

Treatment

The skin infection is usually treated with an antifungal medicine called itraconazole. It is taken by mouth and continued for 2 to 4 weeks after the skin lesions have cleared. You may have to take the medicine for 3 to 6 months.

Fluconazole is used in patients who do not respond to itraconazole. Systemic or disseminated infection is often treated with amphotericin B, or sometimes itraconazole. Therapy for systemic disease can last up to 12 months.

Expectations (prognosis)

With treatment, full recovery can be expected. Disseminated sporotrichosis is more difficult to treat and requires chemotherapeutic agents. Disseminated sporotrichosis can be life-threatening for immunocompromised people.

Complications

In people with a normal immune system:

• Secondary skin infections
• Discomfort

• Disseminated disease
• Lung and breathing problems (such as pneumonia)
• Bone infection
• Arthritis
• Meningitis
• Complications from medications -- amphotericin B can have serious side effects

Calling your health care provider

Call for an appointment with your health care provider if you develop persistent skin lumps or skin ulcers. If you know that you have been exposed to vegetation, mention this to your health care provider.

Prevention

Safer sex behavior can help prevent infection with HIV, the virus that causes AIDS. People with compromised immune systems should try to minimize skin injury by taking measures like wearing thick gloves while gardening.

References

Kauffman CA. Sporotrichosis. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap. 358.