Detection of Histoplasma capsulatum DNA in Lesions of Chronic Ocular Histoplasmosis Syndrome

Objective To evaluate choroidal lesions in histological sections from the enucleated eye of a patient with chronic ocular histoplasmosis syndrome for the presence of Histoplasma capsulatum DNA. Methods Laser-capture microdissection was used to procure cells from macular and midperipheral choroidal lesions in a deparaffinized hematoxylin-eosin–stained section prepared from the enucleated left eye of a patient with an ipsilateral choroidal melanoma and bilateral chronic histoplasmosis syndrome. The captured cells were initially subjected to polymerase chain reaction (PCR) amplification using a pair of primers unique to each end of the nucleotide sequences that are complementary to the DNA known to flank the internal transcribed spacer regions of the ribosomal RNA genes of H capsulatum. This product was then reamplified using a second set of internally situated nested primers. The results were compared with a positive control sample of H capsulatum DNA and with a negative microdissected sample from noninflamed choroid in the same slide. Results Products of H capsulatum DNA were identified in both samples of microdissected tissue and the positive control. They were absent in the negative control. Conclusion The observations provide molecular biological evidence linking the chronic choroidal lesions to earlier infection by H capsulatum .