What stains can be used to identify cryptococcus in tissue sections?

• A. Gram, Ziehl-Neelsen, mucicarmine
• B. GMS, PAS, mucicarmine
• C. H&E
• D. Alcian blue, Van Gieson, Masson's trichrome

Answer: (B)

Staining cryptococcus relies on highlighting both the organism itself and its distinctive capsule. Gomori methenamine silver and PAS are classic stains for fungi: GMS colors fungal cell walls black, while PAS turns fungal polysaccharides pink to magenta, making the yeast easy to see in tissue. Mucicarmine is particularly helpful here because it stains the cryptococcal capsule a bright pink, red, or rose color, emphasizing the capsule that is characteristic of Cryptococcus neoformans. Together, these stains allow you to recognize the organism and its capsule, which is a strong diagnostic clue.

Other stain groups aren’t as useful for identifying cryptococcus in tissue. Gram and Ziehl-Neelsen are mainly for bacteria and acid-fast organisms, not for reliably detecting cryptococcal yeast in tissue sections. Hematoxylin and eosin is a routine stain that may show yeasts, but it isn’t specific for cryptococcus and can miss the capsule. The connective tissue stains listed don’t highlight fungal organisms at all.