Histopathology Diagnosis of Filamentous Fungi

AbstractPurpose of ReviewInvasive fungal diseases (IFDs) are challenging to treat and early diagnosis is important. No single laboratory test is ideal. A proven diagnosis of IFD requires a microbiological and/or histopathological demonstration of fungi. Histopathology examination is rapid and cost effective but lacks specificity for the diagnosis of filamentous fungi. Ancillary techniques can enhance accuracy.Recent FindingsDiagnosis on histopathology is based on the diagnosis of the mould and the tissue reaction. The filamentous fungi can be classified as hyaline septate, hyaline pauci-septate and pigmented (dematiaceous). The tissue reaction helps in differentiating from colonization/contamination and depends on the immune status of the host. Histopathology provides a rapid, though presumptive, diagnosis and may be the only means of diagnosis when culture studies are not available or negative. The morphology diagnosis is aided by histochemistry with periodic acid-Schiff, Gomori methenamine silver and Masson Fontana stains. The tissue response may be allergic mucin or mycetoma, abscess/granuloma, infarct/haemorrhage or angioinvasion/perineural invasion. The low fungal burden, artefacts in morphology due to distortion of hyphae during processing, masking of pathogens by the tissue reaction and lack of immune response in immunosuppressed hosts pose problems in diagnosis. Histopathology alone cannot differentiate the genera from the species, which is important for treatment dec...
Source: Current Fungal Infection Reports - Category: Infectious Diseases Source Type: research