OBJECTIVEs: Non-invasive fungal sinusitis forming fungus balls in the paranasal cavities, is the most common type of the fungal sinusitis. The fungus balls are composed by filamentous fungi mostly, but they may not be identified by culture in many cases. And it is difficult to accurately distinguish between Aspergillus spp. and other filamentous fungi by GMS staining. So we conducted fugus ball using molecular identification to know the epidemiology of non-invasive fungal sinusitis.
METHODS:It was extracted 72 samples of formalin-fixed paraffin-embedded (FFPE) sections of fungus ball removed from paranasal sinuses at Toho University Omori Medical Center in Tokyo, from 2002 to 2016. All 72 were diagnosed as fungal sinusitis of filamentous fungi by histopathological examination. DNA was detected using a conventional polymerase chain reaction (PCR) method using Panfungal primer targeting the 18S/ITS1 rRNA gene and Aspergillus primer targeting the 28SrRNA gene. And the resulting amplification products were prepared for sequence analysis and BLAST analysis. 
RESULTS: PCR with Panfungal primer successfully obtained in 39 out of 72 samples (positive ratio: 54.2%). Genes of Aspergillus species were detected in 16 samples, of Basidiomycota (such as Shyzophillum commune) in 11, of Candida glabosa in 6, of Cladosporium spp. in 2, of Malassezia restricta in 1. And PCR products with Aspergillus primer was positive in 41 out of 72 samples (56.9%), and 37 of them were suggested as Aspergillus spp.. And as a result of two PCRs, fungal DNA was successfully amplified from 57 out of 72 samples (79.2%), including 39 samples of Aspergillus spp..
CONCLUSION: PCR technique using FFPE sections enabled retrospective study of causative fungi of fungal sinusitis, even in cases which had negative result by culture. In present study, Aspergillus spp. were supposed to be the most common causative fungi of fungal sinusitis. But in some cases, genes of Basidiomycota was identified by panfungal primer, and that might be because of the humid atmosphere in Japan.

Molecular analysis of paranasal fungus ball in Japan using formalin-fixed paraffin-embedded sections