Dermatologic Manifestations of Coccidioidomycosis 

Coccidioidomycosis is caused by Coccidioides immitis, a dimorphic soil fungus native to the San Joaquin Valley of California, southern portions of Arizona, northern portions of Mexico, and scattered areas in Central America and South America.

C immitis propagates as a saprophyte and as a parasite. In soil, it grows as a mold with branching septate hyphae. When the soil is disturbed, the hyphae fragment, which forms extremely hardy structures called arthroconidia, can become airborne. If inhaled by animals or humans, the arthroconidia can reach the pulmonary alveoli and transform into thick-walled, multinucleate spherules, which form septa and produce hundreds to thousands of uninucleate endospores. Each endospore is capable of producing new spherules or mycelia.

Rarely, disseminated coccidioidomycosis with cutaneous involvement may clinically mimic a cutaneous T-cell lymphoma.

Go to Coccidioidomycosis and Ocular Coccidioidomycosis for complete information on these topics.

The triad of fever, erythema nodosum, and erythema multiform may occur. Erythema nodosum and erythema multiform have a strong predilection for female patients. Migratory arthralgias are common.

The skin is the most common site of dissemination.

Involvement ranges from superficial maculopapules, keratotic nodules, and verrucous ulcers to subcutaneous fluctuant abscesses. (Nonhealing skin lesions may need to be evaluated by means of biopsy.)

The lesions have a predilection for the nasolabial fold.

Erythema nodosum and erythema multiforme may occur; as previously stated, these have a strong predilection for female patients. Erythema nodosum may manifest as painful subcutaneous nodules and are typically located on the lower extremities. Erythema nodosum may be the first sign of systemic disease. Less commonly, erythema multiforme may develop instead of erythema nodosum, resulting in the typical target lesions. The triad of fever, erythema nodosum, and arthralgias is called desert rheumatism.

Buot et al reported finding specific cutaneous lesions of coccidioidomycosis during placement of a ventricular cardiac shunt for chronic meningitis.^[1]

Testing is available in the United States for assessing the cellular immune response in persons with coccidioidomycosis. Data suggest that archived coccidioidin retains its potency and specificity and that in vitro tests of coccidioidal immunity may have utility in the measurement of coccidioidal cellular immunity.

A dermal delayed-type hypersensitivity reaction to coccidioidin is highly specific for coccidioidal infection. However, a positive result may not be related to currently acquired disease, because, in most persons, this skin test result remains positive for life after infection.

Although skin test results are useful for epidemiologic studies, the test has important limitations when it is used as a screening procedure for recent infections with C immitis.

In patients in whom coccidioidomycosis is diagnosed with the help of other tests, the results of skin testing may have prognostic significance.

With skin testing, the induration of the skin is measured at 24 hours and 48 hours after coccidioidin is injected intradermally. An induration greater than 5 mm is considered reactive. Erythema at the injection site does not aid in the diagnosis of coccidioidomycosis.

Cutaneous coccidioidomycosis with verrucous nodules tends to have an overlying hyperplastic epidermis with a dermal granuloma. Characteristic spores may be evident in the granuloma. Caseation necrosis may also be present.^[2]

Primary inoculation disease results in a dense, mixed, inflammatory dermal infiltrate with occasional giant cells and the formation of small abscesses. Spores may be evident, although hyphae are less likely to be present.

The occasionally associated erythema nodosum has typical histologic features, with no alterations suggestive of coccidioidomycosis. The same is true of erythema multiforme, which is less commonly linked to coccidioidomycosis.

The need for surgery is determined by the nature of specific lesions on a case-by-case basis, because the manifestations, locations, and severity of progressive forms of coccidioidomycosis vary greatly among patients.

In some patients, especially those with extensive dermal involvement, debridement and drainage of the infected sites may be critical in controlling the infection.

A reason for performing this procedure may be that the spherule wall, a strong stimulus for inflammation, cannot be degraded easily or cleared from large coccidioidal lesions by macrophages and other elements of the reticuloendothelial system.

Therefore, even if therapy is effective in arresting fungal proliferation, fungal debris that is already present may continue to cause tissue destruction until it is surgically removed.