IN-SITU HYBRIDIZATION FOR ASPERGILLUS AND PENICILLIUM IN ALLERGIC FUNGAL SINUSITIS - A RAPID MEANS OF SPECIATING FUNGAL PATHOGENS IN TISSUES

Allergic fungal sinusitis (AFS) is a serious form of sinonasal fungal disease that is commonly associated with Aspergillus or Dematiaceous f ungi, This study was performed to determine the incidence of Aspergill us or Penicillium in AFS by using in situ hybridization (ISH) for Aspe rgillus and Penicillium ribosomal RNA (rRNA). The Fontana-Masson melan in stain (FMMS) was also used to detect pigmented fungi (A. niger and Dematiaceous fungi), ISH was performed on 26 patients: 17 AFS cases wi th histologic evidence of fungi, 5 AFS cases without histologic eviden ce of fungi, 3 cases of invasive fungal sinusitis (IFS), and I case of fungus ball. Nine AFS specimens with histologic evidence of fungi wer e ISH positive, Positivity was also noted in two of three IFS cases, w hile no staining was seen in the fungus ball and in six AFS specimens without fungi demonstrable by silver stains, Six ISH-positive cases we re FMMS positive, suggesting A. niger. Five ISH-negative AFS specimens were FMMS positive, suggesting Dematiaceous fungi, In summary, many A FS patients in our institution demonstrate Aspergillus/Penicillium org anisms. Ancillary techniques may help identify fungi responsible for A FS if cultures are negative or not performed, ISH for rRNA is a useful means for rapidly speciating fungi in human tissues.