Before suggesting a diagnosis what do you need to know?
CD4+ count, as many infections found in HIV are dependent on how strong or weak the host immune system is. In this case this patients CD4+ count is only 100 cells / mm3.
What did / does PCP stand for?
Classically, PCP was the acronym for pneumocystis carinii pneumonia but, the causative organism was reclassified as pneumocystis jirovecii. Strictly speaking, pneumocystis carinii refers to a species found in rats, while pneumocystis jirovecii refers to the human isolate. However, physicians have been slow to adopt the updated terminology, and there continues to be widespread use of the term PCP; the post-hoc justification for its use is that it stands for pneumocystis pneumonia.
What is the most likely diagnosis in this case?
In a HIV+ patient with reduced CD4+ count these findings are highly suggestive of pneumocystis pneumonia which was confirmed in this case.
Under what CD4+ count should PCP be considered?
Below 200 cells/mm3.
True or false: this case is typical in that pleural effusions are absent.
True: Pleural effusions are normally not a feature being seen in less than 5% of cases.
There is hazy, predominantly perihilar mid and upper zone opacification with some interstitial prominence. A few discrete cysts (pneumatocoeles) measuring up to 1 cm can be seen. No pleural effusion. No obvious nodal enlargement.