Presumptive diagnoses are based on reflex association. For example, patients with HIV who have symptoms of community acquired pneumonia most likely have an infection with Pneumocystis (carinii) jiroveci pneumonia (PCP). In a case report published in IDCases, researchers present a case of an elderly woman with HIV who was believed to have PCP on the basis of her history of HIV; however, she had a clinical diagnosis of influenza B. Using this case, study authors highlighted that while diagnostic associations are helpful in suggesting diagnostic possibilities, they must be supported by clinical correlation of characteristic clinical features.

A 71-year-old woman with HIV who was receiving highly active antiretroviral therapy presented with a 2-day history of shortness of breath and dry cough. She complained of fever, chills, myalgias, and profound malaise. Her medical history also included diabetes and chronic obstructive pulmonary disease. Recent CD4 count was 258, with an undetectable viral load.

The correct diagnosis was made by demonstrating influenza B using polymerase chain reaction in respiratory secretions and in bronchoalveolar lavage fluid culture. Because the clinical presentation was fully explained by a diagnosis of influenza, there was no need to search for an alternate diagnosis of PCP; however, several more investigative tests were performed for this case.

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While PCP presents with increasing shortness of breath over several days, it has little or no symptomology involving fever with chills and no extrapulmonary findings. Nonetheless, repeat computed tomography (CT) of the chest was performed, even though chest CT scan findings of ground-glass opacities did not favor PCP diagnosis. Ground-glass opacities are more common in influenza pneumonia.

Bronchoalveolar lavage findings were nonspecific with “fungal elements morphologically suggestive of Aspergillus spp” and “Aspergillus pneumonia has a very different appearance on [chest radiographs] and chest CT scans than was the case here,” noted the researchers. Furthermore, serum [galactomannan] levels increased in Aspergillus pneumonia were not elevated. The exudate obtained by bronchoalveolar lavage was not the “typical eosinophilic exudate” of PCP and silver staining was negative for PCP, they added.

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The most important diagnostic test for PCP is for β 1,3 D-glucan, which was negative times 3 in this case.

False diagnostic associations may result in misdiagnosis, warned the researchers. “Clinical correlation is essential in assessing the relevance of the patient’s history and physical findings in making a clinical presumptive diagnosis,” they stated.


Cunha BA, Chawla K, Jimada I. HIV adult with fever and shortness of breath: Influenza B misdiagnosed as Pneumocystis (carinii) jiroveci pneumonia (PCP). IDCases. 2019;17:e00543.