Pneumocystis, Jiroveci Pneumonia

Pneumocystis, Jiroveci Pneumonia

Jud W. Gurney, MD, FACR

Axial CECT shows diffuse ground-glass opacities image with lobular sparing. Small holes image may represent early pneumatoceles.

Coronal CECT reconstructions shows diffuse perihilar distribution of ground-glass opacities image and small pneumatoceles image.


Abbreviations and Synonyms

  • Pneumocystis pneumonia (PCP)


  • Opportunistic fungal infection often affecting individuals with T-cell immunodeficiency

    • 2 major forms: Trophozoites and cysts


General Features

  • Best diagnostic clue: Diffuse symmetric ground-glass opacities in hypoxic immunocompromised patient

  • Patient position/location

    • Diffuse perihilar with peripheral sparing

    • Less common upper lobe predominant with cysts

  • Morphology: Ground-glass opacities with cysts (30%)

CT Findings

  • Morphology

    • Ground-glass is dominant finding

      • Diffuse infections (predominantly PCP) is most common cause of isolated diffuse ground-glass opacities

    • Superimposed intralobular and smooth interlobular septal thickening less common, results in “crazy-paving” pattern

    • Cysts (30%)

      • Thin-walled, usually in ground-glass opacities

      • Usually upper lobe distribution

      • Predispose to pneumothorax

      • With successful treatment, resolve over 5 months

      • Rarely described in non-AIDS PCP

    • Atypical patterns (5-10%) such as multiple nodules (some with cavitation), asymmetric consolidations or rarely, dominant reticular opacities

      • Multiple nodules (may cavitate)

      • Asymmetric consolidation

      • Reticular (interlobular and intralobular) opacities rarely dominant finding

  • Distribution

    • AIDS

      • Ground-glass opacities symmetric and diffuse with sparing of lung periphery 40%

      • Mosaic attenuation pattern 30%

      • Upper lobe distribution in some; may be associated with aerosolized pentamidine prophylaxis

    • Non-AIDS: Often spares 1 lung zone (upper, middle, lower)

    • Prior irradiated lung protected: PCP will develop only outside radiation ports

  • Other

    • Adenopathy uncommon (10%), short axis diameter > 1 cm

      • More common with other fungal or tuberculous infection

    • Tree-in-bud pattern not present

      • Consider bacterial pneumonia, aspiration, or endobronchial tuberculosis

    • Pleural effusion rare

  • In AIDS, confidant diagnosis can be made in 95%

Radiographic Findings

  • May be normal

  • Spontaneous pneumothorax in patients with AIDS = Pneumocystis pneumonia

Nuclear Medicine Findings

  • Historically, gallium scan used for questionable cases, now replaced by CT due to long imaging times (24 hours)

    • Widespread lung activity is present with PCP

Imaging Recommendations

  • Best imaging tool: Extremely rare to have PCP with normal HRCT examination


Hypersensitivity Pneumonitis

  • Antigen source identified with careful work and personal history

    • Onset of dyspnea and nonproductive cough tends to be more subacute or chronic

    • Hypoxia often more mild and fever less common

  • Diffuse ground-glass most common imaging manifestation

  • Ill-defined centrilobular nodules more common than in PCP

  • Air-trapping common at expiratory CT, uncommon with PCP

  • May also have cysts

Lymphocytic Interstitial Pneumonia

  • Increased frequency in AIDS, especially in children

  • Thin-walled cysts, ground-glass opacities, and centrilobular nodules

  • Lymph nodes may be enlarged, uncommon with PCP

Diffuse Alveolar Hemorrhage

  • Anemia common

  • Clinical history, tissue sampling, and laboratory investigation required to differentiate different etiologies of DAH

  • Diffuse or extensive bilateral ground-glass and consolidative opacities similar to PCP

Cytomegalovirus Pneumonitis

Sep 20, 2016 | Posted by in RESPIRATORY IMAGING | Comments Off on Pneumocystis, Jiroveci Pneumonia

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