Histology: Punch biopsy or excisional biopsy specimens show a diffuse granulomatous inflammatory infiltrate. Pseudocarcinomatous epithelial hyperplasia often overlies the granulomatous infiltrate. Within the granulomatous portion of the dermal infiltrate are the characteristic spherules that contain endospores. The spherules are thick walled and can readily be seen on specimens routinely stained with hematoxylin and eosin stain. The spherule can be highlighted with the use of a silver stain.
Pathogenesis: Coccidioidomycosis is caused by the soil-dwelling fungus, C. immitis. Endemic to the southwestern United States, Central America, and parts of South America, this fungus is found in the environment in its mycelial or mold phase. It produces white, light, and fluffy arthrospores. These arthrospores are highly infectious. Once inhaled, this dimorphic fungus turns into its yeast form. The yeast form is made of thickwalled spherules with multiple, centrally located endospores that can be released from the host by coughing or by drainage of an abscess. The resulting endospore readily converts back to its mycelial phase and can infect another host.
Treatment: The azole antifungals fluconazole and itraconazole are first-line therapies for coccidioidomycosis. Treatment typically lasts 6 to 12 months; prolonged therapy may be required in some cases. Severe, life-threatening cases and those refractory to azole antifungal medications are usually treated with amphotericin B. Adjunctive surgical treatment can be used to debride abscesses and remove isolated pulmonary disease.
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