Pneumocystis Carinii Pneumonia Pneumocystis Jerovecii
General Considerations
- Most common cause of interstitial pneumonia in immunocompromised patients
- Organism
- Protozoan / fungus Pneumocystis carinii (jiroveci)
Predisposed
- AIDS
- Debilitated
- Premature infants
- Children with hypogammaglobulinemia
- Other immunocompromised patients
- Congenital immunodeficiency syndromes
- Lymphoproliferative disorders
- Organ transplant recipients
- Patients on long-term corticosteroid therapy
- Patients on chemotherapy for cancer
Associated infections
- CMV
- Mycobacterium avium-intracellulare (MAI)
- Herpes simplex
Clinical Findings
- Severe dyspnea and cyanosis
- Subacute insidious onset of malaise and slight cough (frequent in AIDS patients)
- Respiratory failure
- WBC slightly elevated (polys)
- Lymphopenia (50%) indicates poor prognosis
Imaging findings
- Normal CXR in 10-40%
- Bilateral diffuse symmetric finely granular / reticular interstitial / airspace infiltrates in 80%
- Characteristic central location
- Rapid progression to diffuse airspace disease
- Resembles non-cardiogenic pulmonary edema
- Pleural effusion and hilar lymphadenopathy are uncommon
- Atypical pattern in 5%
- Isolated lobar disease / focal parenchymal opacities
- Lung nodules ± cavitation
- Hilar / mediastinal lymphadenopathy
- Thin- / thick-walled cysts
- Cavities with predilection for upper lobes
CT Findings
- Patchwork pattern (56%)
- Bilateral, asymmetric patchy mosaic appearance
- Ground-glass pattern (26%)
- Bilateral, diffuse air-space disease in symmetric distribution
- Interstitial pattern (18%)
- Bilateral, symmetric / asymmetric, reticular markings (thickening of lobular septa)
- Abnormal air-filled spaces (38%)
- Pneumatocoeles
- Thin-walled spaces without lobar predilection resolving within 6 months
- Subpleural bullae due to emphysema
- Thin-walled cysts
- Necrosis of pneumocystis granuloma
- Pneumothorax (13%)
- Lymphadenopathy (18%)
- Pleural effusion (18%)
Pulmonary nodules and cavities
- Usually due to malignancy
- Leukemia, lymphoma
- Kaposi sarcoma
- Metastasis
- Or septic emboli
- Pulmonary cavities usually due to superimposed fungal / mycobacterial infection
Nuclear medicine
- Bilateral and diffuse Ga-67 uptake without mediastinal involvement prior to roentgenographic changes
Course
- Usually responds to therapy in 5-7 days
- Effect of prophylactic use of aerosolized pentamidine
- Redistribution of infection to upper lobes
Complications
- Cystic lung disease
- Central location to cysts
- Spontaneous pneumothorax, frequently bilateral (6-7%)
- Disseminated extrapulmonary disease (1%)
- Punctate / rimlike calcifications within enlarged lymph nodes and abdominal viscera
DDx
- Non-cardiogenic pulmonary edema
- TB
- MAI infection
Diagnosis
- Sputum collection
- Bronchoscopy with lavage
- Transbronchial or transthoracic or open lung Bx
Pneumocystis Pneumonia. There is bilateral, mostly reticular, interstitial lung disease (white circles). This is a similar picture to that of congestive heart failure under other clinical circumstances.