HRCT-features of Pneumocystis jiroveci pneumonia and their evolution before and after treatment in non-HIV immunocompromised patients

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Abstract

Objective

This study retrospectively analyzes the characteristics and kinetics of pulmonary changes in Pneumocystis jiroveci pneumonia (PJP) before and after treatment as depicted by thin-section-CT in HIV-negative patients.

Materials and methods

Serial CT scans of 84 consecutive HIV-negative PJP patients were reviewed retrospectively encompassing a median follow-up of 76 (range, 37–506) days. Along with underlying disease and time span between the onset of symptoms and specific antimicrobial therapy, early and late pulmonary CT-findings were evaluated.

Results

Imaging findings at initial diagnosis differed from those in the posttherapeutic setting. In the acute (initial) PJP-phase, most frequent finding was symmetric, apically distributed ground glass opacities (GGO) with peripheral sparing 43% (n = 36). These initial changes resolved up to 1st follow-up-examination in 57% (n = 48), and finally in all except for two patients after a median period of 13 (mean 26, range 1–58) days following application of specific therapy. In 42% (n = 35) architectural distortions occurred, but they resolved after a median period of 27 (mean 60, range 11–302) days. Only in 9 patients, complete resolution could not be documented. Significant correlations of the underlying disease or the time span between the onset of symptoms and specific antibiotic therapy and morphologic kinetic could not be found.

Conclusion

Thin-section CT-findings of PJP usually resolve soon after onset of specific therapy. Postinfectious fibrosis rarely occurs following PJP in HIV-negative patients.

Introduction

Pneumonias are among the most frequent, life threatening infectious complications in immunocompromised patients. The incidence of pneumonia by Pneumocystis jiroveci, the former carinii (PJP) is estimated to be below 2% in patients with solid tumors and collagen vascular diseases undergoing steroid therapy. In transplant recipients, an incidence of 5–10% is reported [1]. The most common symptoms include progressive dyspnoea, non-productive dry cough and a light fever [2]. A thin-section CT is considered the most reliable imaging modality in detecting and differentiating pneumonia in immunocompromised patients [3], [4]. Given the wide availability of CT-scanners, follow up-examinations for therapy monitoring in severely ill patients with infectious pulmonary complications can be easily performed. As a consequence, knowledge about the normal temporal course of PJP is essential, to assure correctness of diagnosis and assess appropriate response to therapy. Furthermore, it seems relevant, whether a chronic lung disease such as fibrosis is likely to be a consequence of a preceding PJP. Pulmonary fibrosis including multiple thin walled cysts, which is variable in occurrence and severity, and is even radiographically observed in 10–34% of PJP-patients [5]. However, there is little data existent about the morphology of late changes in HIV-negative patients, as this feature has mainly been described in patients with AIDS both by radiologists and by pathologist as a late sequelae of PJP and as a common cause of spontaneous pneumothorax [1], [6], [7], [8], [9].

The CT-morphology of acute PJP has been extensively analyzed and described as multifaceted. The most frequent pattern in the early phase of the disease is extensive ground glass opacity (GGO) with predilection for the apical and central lung regions [3], [6], [10], [11], [12], [13]. To our knowledge no data exists about the course, duration and morphology of chronic pulmonary changes as depicted on thin-section-CT in non-HIV immunocompromised patients with PJP.

The aim of this retrospective study was to determine the frequency, morphology and the evolution of pulmonary findings in PJP as depicted by thin-section-CT in non-HIV patients.

Section snippets

Patients

Patients for the study were identified by positive broncho-alveolar lavage (BAL) for P. jiroveci in the database of our institute for microbiology. Database search covered the time period from January 2002 to June 2009. A total of 187 PJP patients were identified, 84 were included in the study. Inclusion criteria were the availability of chest-CT-examinations before (CT0), during and after PJP, the absence of HIV-infection, pulmonary co-infection or co-morbidity during the examined time period,

Results

All of the 187 patients with BAL positive for P. jiroveci had undergone chest-CT within a median time frame of ±1 (range ±6) days. Of these 187 patients, 89 were excluded because of lacking CT0 performed before onset of pulmonary symptoms. Nine of the remaining 98 patients had to be excluded for suspected or proven coinfection or pulmonary comorbidity such as toxic lung damage due to medication (n = 2), transfusion induced lung injury (n = 1), pulmonary aspergillosis (n = 2), CMV-infection (n = 2),

Discussion

Chest CT scans are increasingly performed for diagnosis and therapeutic monitoring of pneumonia in immunocompromised patients. To our knowledge, to date no data about the temporal course of pulmonary CT findings in non-HIV-PJP have been reported. In our retrospective study morphological changes in 84 PJP patients were followed over a period of up to 506 days.

The initial appearance of PJP was similar to previously reported symmetric, apically distributed GGO with perihilar location, a mosaic

Conclusion

Signs of acute PJP often resolve quickly after the application of specific antimicrobial therapy. Architectural distortions do not regularly occur following PJP and are often reversible in HIV-negative patients receiving adjunctive corticosteroids.

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