Discrepancy between histology and culture in filamentous fungal infections

Although the incidence of non-Aspergillus filamentous fungal infections has increased, there is little data regarding the correlation between the results of histologic analysis and those of microbiologic culture in clinical practice. We investigated the results of fungal cultures inoculated with tissue specimens that had been found to have fungal hyphae on histologic examination at a university-affiliated tertiary care hospital. Culture studies were requested for microbiologic diagnosis for 122 (31%) of 393 patients with histologic evidence of the presence of filamentous fungal infections. In 53 (43.4%) out of the 122 specimen, fungi were recovered and identified. In 9 (17%) out of the 53 cases, the histology and culture results were discordant. These data serve to remind physicians of the need for obtaining fungus cultures in these types of cases.