Thoracic Disorders in the Immunocompromised Child

Pediatric Lower Respiratory Tract Infections: Imaging Guidelines and Recommendations

Lower respiratory tract infection (LRTI) remains a major cause of morbidity and mortality in children. Various organisms cause LRTI, including viruses, bacteria, fungi, and parasites, among others. Infections caused by 2 or more organisms also occur, sometimes enhancing the severity of the infection. Medical imaging helps confirm a diagnosis but also plays a role in the evaluation of acute and chronic sequelae. Medical imaging tests help evaluate underlying pathology in pediatric patients with recurrent or long-standing symptoms as well as the immunocompromised.

Spectrum of imaging findings in pulmonary infections. Part 1: Bacterial and viral

Chest radiography is generally the first imaging modality used for the evaluation of pneumonia. It can establish the presence of pneumonia, determine its extent and location, and assess the response to treatment. Computed tomography is not used for the initial evaluation of pneumonia, but it may be used when the response to treatment is unusually slow. It helps to identify complications, detect any underlying chronic pulmonary disease, and also to characterise complex pneumonias. Although not diagnostic, certain imaging findings may suggest a particular microbial cause over others. Knowledge of whether pneumonia is community-acquired or nosocomial, as well as the age and immune status of the patient, can help us in narrowing the differential diagnoses. The purpose of this article is to briefly review the various pulmonary imaging manifestations of pathogenic organisms. This knowledge along with clinical history and laboratory investigations of the patient may help in guiding the treatment of pneumonia.

Clinical and imaging considerations in primary immunodeficiency disorders: an update

Primary immunodeficiencies are a group of genetically determined disorders with diverse presentations. The purpose of this review is to provide a practical and brief description of a select number of these diseases and to discuss the important role the radiologist can have in making an early diagnosis and in detecting and following disease complications. The role of diagnostic imaging and informed performance and interpretation are vital in the diagnosis, surveillance and management of all primary immunodeficiency disorders.

Infections

Lower respiratory tract infection is a very common illness in children and is a significant cause of morbidity and mortality. Clinical signs and symptoms are nonspecific especially in infants and younger children and some even present with nonrespiratory complaints. Infectious agents causing pneumonia is not limited to viruses and bacteria, but it could also be due to Mycoplasma, Mycobacteria, fungi, protozoa, and parasites. Coinfection with two or more microbial agents can also occur. The etiologic agent of lower respiratory infection in a child is often difficult to obtain, but the patient’s age can help narrow the possible cause. Microbiological tests are important but could be difficult to obtain especially in younger children. Various medical imaging modalities not only play an important role as an aid in diagnosis but can also help during and after therapy. Imaging can also help evaluate complications to pneumonia and exclude other causes of respiratory distress including underlying developmental anomalies, foreign body, gastroesophageal reflux disease, and aspiration. In this chapter, the imaging modalities utilized in the detection of pulmonary infections will be discussed. The spectrum of typical imaging findings for various etiologic agents in both immunocompetent and immunocompromised children will be presented.

Pulmonary infections

This paper reviews the most common imaging findings of pulmonary infection in children. Pneumonia is a leading cause of mortality in children in developing and industrialized countries. While the imaging findings usually are nonspecific, correlation with the patient's age, immune status and pertinent history can limit the differential diagnoses. The paper will review the common and unique features of pneumonia caused by specific organisms and in specific patient populations.

Bronchiectasis secondary to primary immunodeficiency in children: longitudinal changes in structure and function

BACKGROUND

Primary immunodeficiency is a common cause of bronchiectasis in children. The term bronchiectasis suggests an irreversible process; however, disease progression following treatment is controversial. The aim of this study was to evaluate the progression of bronchiectasis in children with primary immunodeficiency after institution of treatment.

METHODS

A retrospective review of case notes of children with primary immunodeficiency was undertaken to identify patients with confirmed bronchiectasis. Children who had two high-resolution computed tomography scans of the chest (HRCT chest) with an interval of at least 2 years were identified. The HRCT-chest scans at diagnosis and follow up were scored using a Bhalla score. Spirometry results (FEV1, FVC, and FEV1:FVC ratios) were related to HRCT-chest scores, where available. Statistical analysis was by Wilcoxon signed rank test and Spearman's rank order correlation.

RESULTS

Eighteen subjects were studied. The diagnosis of primary immunodeficiency was established at median (range) age 3.4 (1-13) years, and bronchiectasis at 9.3 (3.1-13.8) years. There was no significant difference between baseline and follow-up median (range) HRCT-chest scores (6 [1-13] and 7.5 [0-15], P = 0.21) respectively. The follow-up FEV1 and FVC percent predicted median (range) were significantly higher than baseline (86% [49-124%] vs. 75% [36-93%], P < 0.005, and 86% [47-112%] vs. 78% [31-96%], P < 0.05), respectively; there was no significant difference between baseline and follow-up FEV(1):FVC ratios. There was no significant correlation between HRCT-chest score changes and FEV1 or FVC changes.

CONCLUSIONS

Bronchiectasis secondary to primary immunodeficiency in childhood is not always a progressive condition, suggesting a potential to slow or prevent disease progression with appropriate treatment.

Pulmonary infections following bone marrow transplantation: High-resolution CT findings in 35 paediatric patients

PURPOSE

The purpose of this study was to assess the high-resolution CT findings of paediatric patients who had pulmonary infections following bone marrow transplantation (BMT), and to evaluate the differential diagnosis through high-resolution CT of the various pathogens responsible for pulmonary infections after BMT.

PATIENTS AND METHODS

The study included 35 consecutive patients who had documented pulmonary infection, high-resolution CT of the chest performed within 24h of the beginning of symptoms, and proven diagnosis within 1 week of the onset of symptoms. The pulmonary infections were due to viruses (n=16), bacteria (n=9), fungi (n=9), and protozoa (n=1). Two radiologists analyzed the CT scans and reached final decisions regarding the findings by consensus.

RESULTS

Four patients with confirmed pneumonia had normal high-resolution CT scans. Regarding the viral infections, the most frequent features were areas of ground-glass attenuation (43.7%) and small centrilobular nodules (31.2%). Airspace consolidation (88.9%), small centrilobular nodules (22.2%) and ground-glass attenuation (22.2%) were the most frequent findings in patients with bacterial pneumonia following BMT. Large nodules were seen in 66.7% of the patients with fungal pneumonia, and in only one case of virus infection. The "halo sign" (n=5) was seen only in patients with fungal pneumonia.

CONCLUSION

In conclusion, the main causes of pulmonary infection in paediatric patients following BMT share similar high-resolution CT findings. Large nodules and "halo sign" are more common in patients with fungal infections.

Genetic causes of bronchiectasis: primary immune deficiencies and the lung

Primary immune deficiencies (PID) comprise a heterogeneous group of genetically determined disorders that affect development and/or function of innate or adaptive immunity. Consequently, patients with PID suffer from recurrent and/or severe infections that frequently involve the lung. While the nature of the immune defect often dictates the type of pathogens that may cause lung infection, there is substantial overlap of radiological findings, so that appropriate laboratory tests are mandatory to define the nature of the immune defect and to prompt appropriate treatment. At the same time, the recent identification of a large number of PID-causing genes now allows early, even presymptomatic diagnosis, thus representing an essential tool for prevention of lung damage. This review article describes the most common forms of PID, their cellular and molecular bases, and the associated lung abnormalities, and reports on available treatment.