What is the presentation of Coccidiomycosis (Valley fever) skin lesions?

Presentation of Coccidioidomycosis Skin Lesions

Coccidioidomycosis skin lesions present in two distinct forms: reactive rashes (erythema nodosum and erythema multiforme) that occur during primary pulmonary infection and do not contain viable fungus, versus disseminated cutaneous lesions (chronic ulcerations, subcutaneous abscesses, nodules, and sinus tracts) that represent tissue-destructive hematogenous spread and indicate serious extrapulmonary disease. 1

Reactive Skin Manifestations (Primary Infection)

These occur during early pulmonary coccidioidomycosis and are immunologic reactions:

• Erythema nodosum and erythema multiforme are the characteristic reactive rashes that develop within a month of endemic exposure 1
• These lesions do not contain viable fungal elements and do not cause permanent tissue damage 1
• They are self-limited and resolve without specific antifungal therapy 1
• Associated with arthralgias (typically symmetrical, distal lower extremities, without joint effusions) 1

Disseminated Cutaneous Lesions (Hematogenous Spread)

These represent true fungal invasion and tissue destruction:

• Chronic skin ulcerations are the most common presentation of cutaneous dissemination 1
• Subcutaneous abscesses and phlegmon indicate soft tissue involvement 2
• Isolated nodules (may appear hyperkeratotic and mimic actinic keratosis or squamous cell carcinoma) 3
• Sinus tracts often result from underlying infection in neighboring lymph nodes, bones, or joints 2
• Varied morphologies including papules, plaques, vesicles, pustules, and nodules 1
• Lesions are focal areas of tissue destruction resulting from acute inflammatory response to actively rupturing spherules 1

Critical Clinical Distinctions

The presence of disseminated skin lesions should immediately prompt investigation for other extrapulmonary sites, as 90% of patients with cutaneous dissemination have concurrent involvement of other organs 2:

• Pulmonary symptoms or radiographic abnormalities may be minimal or completely absent in disseminated disease 1
• Lymph nodes are commonly involved alongside cutaneous lesions 2
• Disseminated lesions are progressive and rarely resolve without medical intervention 1
• They may wax and wane over months to years but typically worsen without treatment 1

Geographic and Temporal Context

• Skin manifestations should be considered in patients with endemic exposure within the preceding month 1
• Endemic areas include arid regions of southwestern United States, Mexico, and Central/South America 1, 4

Diagnostic Approach

• Biopsy of suspicious skin lesions is the most direct diagnostic method for disseminated cutaneous disease 1, 2
• Histologic examination reveals spherules in disseminated lesions but not in reactive rashes 1
• Culture of lesional tissue can confirm diagnosis 2
• Serologic testing (IgG, IgM, complement fixation) supports diagnosis but may be negative early in infection 1