대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

Pneumocystis jirovecii pneumonia (PJP) in AIDS patient

Radiologic Findings

Fig1. Chest PA shows diffuse GGO in both lungs and consolidations in the lower lobes.
Fig2-5. Chest CT shows extensive diffuse GGO and suspicious fine nodules in the whole lung. Patchy decreased parenchymal attenuation are noted in RUL, RML and LUL lingular segment. Also, there are confluent consolidations in the posterior aspect of lower lobes.
Initial radiologic differential diagnosis was hyperacute or acute hypersensitivity pneumonitis, manifesting as a three-density pattern, as correlated with clinical and occupational status. However, he was diagnosed with AIDS during examination, and PJP PCR test was positive. After Cotrim IV + Steroid Pulse therapy, the lesions improved completely.

Brief Review

Pneumocystis jiroveci is an atypical fungus that causes pneumonia in immunocompromised human hosts, and rarely in immunocompetent individuals. The presentation of PJP in a patient with HIV infection is typically subacute, characterized by a slow onset of dry cough and dyspnea. PJP in patients without HIV infection presents as an acute illness associated with severe hypoxia and results in rapid respiratory deterioration and respiratory failure
The radiographic findings of PJP are nonspecific, and in as many as one-third of infected patients they may be normal. The most common high-resolution CT finding of PJP is diffuse GGO with predominantly perihilar or mid zones. Other findings include crazy-paving pattern, consolidation, nodules, cysts and pneumothorax. Air cysts is a pneumatocele that occurs mainly in patients undergoing aerosolized prophylaxis and is usually placed in the upper lobes. If there are atypical imaging findings such as consolidation, small nodules, lymphadenopathy or pleural effusion, other superimposed infections should be considered. Overall, with prompt treatment, survival is good (50-95%).
The three-density pattern on chest CT is characterized by the mixed lung parenchyma of high, low and normal attenuation. This sign is considered to be highly specific for hypersensitivity pneumonitis, but differentiation from other obstructive or infiltrative diseases is necessary. For example, sarcoidosis, atypical infection associated bronchiolitis such as mycoplasma pneumonia, respiratory bronchiolitis, or desquamative interstitial pneumonia (DIP) may also manifest with the three-density pattern.
The occurrence of consolidation, micro and small nodules with centrilobular or random distribution, and halo sign were highly suggestive of CMV pneumonia rather than PJP in AIDS patients.

References

1. Kanne JP, Yandow DR, Meyer CA. Pneumocystis jiroveci Pneumonia: High-Resolution CT Findings in Patients With and Without HIV Infection, AJR. 2012;198: W555-W561
2. CJ Du, J-Y Liu, H Chen, Differences and similarities of high-resolution computed tomography features between pneumocystis pneumonia and cytomegalovirus pneumonia in AIDS patients. Infect Disease of Poverty (2020) 9:149

Keywords

Pneumocystis jiroveci pneumonia,