Pneumocystis pneumonia

The alveoli are filled with an exudate. The apparently empty spaces in the alveoli in this H&E  stain represent P. carinii. This organism usually offers no hazard to the immunocompetent.

Pneumocystis jiroveci, previously known as Pneumocystis carinii is an opportunistic organism causing lung infection. Originally called a trophozoite, it is now classified as a fungus. Some cases of infection were noted in malnourished children in orphanages in Europe in the first half of the twentieth century and subsequently in patient with iatrogenic immunosuppression. Marked increase in awareness of this organism came about with the advent of AIDS in the nineteen eighties. This is not an infection of healthy individuals. The organism is found with frequency in asymptomatic persons. With better treatment, mortality in AIDS patients has dropped from a rate of 20-40% but pneumocystis pneumonia is still a major cause of death. Patients may present with dyspnea, cough, fever, chills, and weight loss. Diagnosis can be made by examining sputum induced by hypertonic saline or examination of bronchoalveolar lavage fluid. Lung biopsy is a diagnostic technique of last resort. Stains used in organ identification include cresyl violet, Diff-Quick, Wright, methamine silver, Papanicoloau and monoclonal antibodies. It is not uncommon for the AIDS patient with pneumocystis pneumonia to also harbor other opportunistic infections such as cytomegalovirus. Many drugs are available for treatment of this disorder including trimethoprim-sulfamethasoxazole and pentamidine.


In this GMS stained section the organisms stain black. PCP has been popularized since

 the advent of AIDS but had previously been reported in nutritionally deficient children.


From the slide collection of the late Dr. Charles Kuhn