Coccidioidomycosis A Cause of Sarcoidosis

BACKGROUND: Sarcoidosis is a granulomatous disease of unknown etiology and coccidioidomycosis is a granulomatous fungal infection endemic to the southwestern United States. Clinical observations on patients with sarcoidosis and coccidioidomycosis simultaneously led to the hypothesis that sarcoidosis can be caused by the fungus Coccidioides. METHODS: Two patients with sarcoidosis and coccidioidomycosis were studied, one prospectively (ie, a patient with sarcoidosis was predicted to develop coccidioidomycosis) and the other retrospectively (ie, a patient with coccidioidomycosis develops sarcoidosis). In addition, a literature review found 5 patients with these 2 diseases, and they were analyzed to establish an archived relationship between the 2 entities. In addition, polymerase chain reaction (PCR) testing for Coccidioides deoxyribonucleic acid (DNA) was performed on tissue from 15 Arizona patients diagnosed with sarcoidosis. RESULTS: Patient 1 was diagnosed with sarcoid in Arizona and followed prospectively. There was no evidence for coccidioidomycosis at diagnosis. This patient was observed for 8 years before he was documented to have disseminated coccidioidomycosis. Patient 2 was retrospectively studied. He was diagnosed with disseminated coccidioidomycosis, but after 3 years, while on antifungal therapy, he developed respiratory failure. A lung biopsy was consistent with sarcoidosis with no evidence of Coccidioides; cultures, histopathology, and serology were all negative. Paradoxically, PCR testing for Coccidioides DNA on tissue taken at the time of the sarcoidosis diagnosis were all negative, including Patient 2 who had proven coccidioidomycosis. CONCLUSIONS: The 2 study patients and 5 case reports from the literature support the hypothesis that Coccidioides can cause sarcoidosis in Arizona. There are similar reports in the literature that Histoplasma can be associated with sarcoidosis. Based on these observations, we propose that sarcoidosis can be caused by endemic fungi in different areas of the United States, coccidioidomycosis in the Southwest and histoplasmosis in the Midwest.