Histoplasmosis-like choroiditis in a nonendemic area: The northwest United States

Purpose: Histoplasmosis is not endemic in the U.S. northwest, but a type of multifocal choroiditis resembling ocular histoplasmosis occurs there. This study was designed to find a group of affected patients and study their clinical characteristics and immunologic responses to Histoplasma antigens. Method: Ten patients were found in the authors' files whose geographic histories made it unlikely that they had ever been exposed to Histoplasma capsulatum and yet they had features of ocular histoplasmosis. They were recalled for examination and testing by lymphocyte-stimulation assay for previous exposure to histoplasmosis. Results: The clinical features of these patients resembled those of patients with ocular histoplasmosis, but their histories and the results of the assay did not support H. capsulatum as the cause of the ocular disease. Conclusion: This study confirmed that there is a type of choroiditis that resembles ocular histoplasmosis but is due to another agent or agents.