SCOTTSDALE, ARIZ. — Think of coccidioidomycosis in patients with a rash, fever, and cough, even if they don't live in the southwestern United States where Coccidioides is endemic.
At least two patients have presented to the Mayo Clinic, Rochester, Minn., with cutaneous manifestations of coccidioidomycosis. Both patients were “snowbirds” who traveled to warmer climates in the southwest during the winter, according to physicians from the Mayo Clinic, Scottsdale, Ariz.
Although this mainly is a lung infection, cutaneous manifestations provide a clue to the diagnosis. “In the last 10 years at the Mayo Clinic in Arizona, I've been impressed by how often the dermatologist has a role to play in the diagnosis of coccidioidomycosis,” Dr. David J. DiCaudo said at a dermatology conference sponsored by Skin Disease Education Foundation.
The desert areas of the southwestern United States and northern Mexico are the prime locations of this fungus, which is found in the western United States, Central America, and south to Argentina. Most U.S. infections occur in Arizona and in California's San Joaquin Valley, where a syndrome with the infection was first recognized and dubbed “valley fever,” said Dr. DiCaudo of the Mayo Clinic, Scottsdale.
The incidence of coccidioidomycosis in Arizona more than tripled in the past decade, with a 56% increase in the past year alone. Droughts in recent years and construction activity stirring up soil and dust probably have contributed to the increase, he suggested. The organism lives in soil as filamentous mycelia that break down into arthroconidia, which can be carried on the wind and inhaled. Once inside people or animals, they transform into the spherule form recognized in biopsy specimens.
Most Coccidioides infections cause no symptoms. Around 40% of infected people develop a mild to moderate influenzalike illness with fever, cough, chills, and arthralgias. Even healthy people can be severely affected and laid low for weeks by the symptoms. Fewer than 1% develops severe infection or dissemination to the meninges or bones, with some deaths.
People of Filipino heritage are hundreds of times more likely to develop severe infection or dissemination, compared with the general population, and African Americans are at increased risk as well, Dr. DiCaudo said. People with compromised immune systems caused by pregnancy, HIV infection, or organ transplant, or those using steroids or other immunocompromising medications also face greater risk with this infection.
The painful red nodules of erythema nodosum are the most common cutaneous manifestation of coccidioidomycosis. They typically appear on the lower extremities 1–3 weeks after the onset of systemic symptoms and suggest a good prognosis.
Other cutaneous symptoms appear earlier. Acute exanthem may appear within the first 24–48 hours of illness. “I've seen several patients who had a florid eruption even before the onset of any other symptom. Days later, they developed fever and cough,” he said.
The acute exanthem can resemble a drug reaction. Associated pruritus may be mild to severe. Lesions on the palms are common. It may last days or weeks.
The infection also can cause Sweet's syndrome, presenting as painful plaques, often but not always on the upper body, associated with fever and peripheral blood leukocytosis. In other settings, Sweet's syndrome commonly is treated with systemic corticosteroids. “It's worth checking to make sure the patient doesn't have coccidioidomycosis first,” because an immunosuppressive drug would increase their risk, Dr. DiCaudo said.
Granulomatous dermatitis can develop early in the course of the disease with widely distributed papules and plaques.
All of these cutaneous symptoms are reactive conditions; no Coccidioides will be found in the skin. The skin symptoms evolve over a period of weeks or months as the patient recovers from the pulmonary infection.
A skin biopsy can be helpful, however, in rare disseminated infection, which typically develops 1–3 months after the onset of illness and can cause nodules, granulomatous plaques, and ulcers on the skin. It can mimic many other diseases including tuberculosis or acne. Even rarer is primary cutaneous infection at the site of inoculation, typically from injury by a laboratory pipette, a splinter, or even a cactus spine.
Serology is the key to diagnosing coccidioidomycosis. Keep in mind that the rash precedes seroconversion, so you may want to retest some patients with negative serologies 2 weeks later, he said. Low titers are common and shouldn't be dismissed.
The IgG antibody test can be positive and the IgM negative during active infection and shouldn't be interpreted as a past infection, he added. The antibodies tend to disappear following recovery, so a positive titer most likely represents acute infection.