Aspergillus in the Papanicolaou stain: morphology, fluorescence and diagnostic feasibility

Aspergillus species exhibit a distinct and clear fluorescence in Papanicola ou-stained cytological samples. The Papanicolaou (PAP) stain enhances the a utofluorescence of cultured aspergilli and allows better cytological recogn ition of the fungus by fluorescence microscopy when it is not easily discer ned from its surroundings by light microscopy. Morphological properties can be better distinguished and facilitate the differentiation of aspergillus organisms from other filamentous fungi. Neither light nor fluorescence micr oscopy, the cytological quality nor the presence of phagocytosed hyphae in alveolar macrophages allow distinction between infection and contamination with Aspergillus species. Only the presence of eosinophilic in inflammation permits a tentative diagnosis of an Aspergillus infection. In conclusion, PAP fluorescence reduces the need for special stains, is superior to and qu icker than other investigative techniques and enhances the sensitivity and specificity of cytological investigation when a rapid and reliable identifi cation of Aspergillus is needed.