Which staining techniques are used for histologic evaluation of Pneumocystis jiroveci pneumonia (PJP)?

Updated: Apr 24, 2019
  • Author: Shelley A Gilroy, MD, FIDSA; Chief Editor: Pranatharthi Haran Chandrasekar, MBBS, MD  more...
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Answer

Answer

Because clinical and radiologic findings are not specific for PJP and because P jiroveci cannot be grown in vitro, histopathologic demonstration is necessary before a definitive diagnosis is established. The following are the staining techniques available for respiratory tract secretions.

Crystal violet, Giemsa, Diff-Quik, and Wright stain are used to detect both the trophozoite and cyst forms but not the cyst wall. Diff-Quik stain demonstrating P jiroveci is seen in the image below.

Diff-Quik stain demonstrating Pneumocystis jirovec Diff-Quik stain demonstrating Pneumocystis jiroveci.

Methenamine silver, toluidine blue, and Gram-Weigert selectively stain the wall of Pneumocystis cysts. Silver Gram stain showing P jiroveci is seen in the image below .

Silver Gram stain showing Pneumocystis jiroveci. Silver Gram stain showing Pneumocystis jiroveci.

Papanicolaou smear may demonstrate a foamy-appearing eosinophilic material surrounding Pneumocystis organisms (as seen in the image below).

Papanicolaou smear of Pneumocystis jiroveci. Papanicolaou smear of Pneumocystis jiroveci.

Some facilities prefer to use direct immunofluorescence using monoclonal antibodies to detect Pneumocystis organisms because it may be more sensitive than histologic staining.


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