Pulmonary infections represent a major cause of morbidity,
hospitalization and mortality (Figure 1) within pediatric population,
and the number of hospital admissions for such pathologies keeps increasing worldwide.
This growth is partly due to the high incidence of human immunodeficiency virus (HIV) and tuberculosis,
and these conditions,
together with other immunodeficiencies,
cause challenges in diagnosis and therapy planning,
and in worst cases treatment failure (1).
Functional tests have for many decades been the main tool to detect and monitor lung changes in pulmonary diseases,
even though they lack sensitivity,
being an indirect approach to analyze lung functionality.
lung imaging represents the best diagnostic tool to evaluate and monitor the localized changes within pulmonary structures,
but our diagnostic instruments still lack standardization of image acquisition and analysis nowadays.
The technical innovation of lung MRI and CT,
together with the consensus in the use of chest x-rays and US,
allow to increase the quality of diagnosis and follow-up of pulmonary infections and,
paying close attention to keep radiation dose to minimum,
all our diagnostic tools can successfully be applied to pediatric population (2).
Overall incidence data of pulmonary infections in pediatric patients are poor because accurate diagnosis is limited by diagnostic methodology,
and they vary for each country due to variable vaccine coverage.
The estimated incidence of low-respiratory tract infections (LRTI) is 30 per 1000 children per year in the UK.
UK data for hospital access of children diagnosed with pneumonia (clinical findings and CXR) during 2001-2002 found overall incidence rates of 14.4 per 10,000 in patients aged 0-16 years per annum and 33.8 for those aged ≤5 years.
Incidence in boys is higher than girls,
as is in children born between 24-28 weeks when compared to those born at term (3).
Most of the hospitalized pneumonia are bacterial (Figura 2).
Viruses are the most common cause of respiratory infection in early childhood ,
and lower respiratory viral infections may present as tracheobronchitis,
bronchiolitis and pneumonia.
About 45% of children hospitalized with a diagnosis of pneumonia have a viral etiology (4).
Most common pathogens are reported on table 1.
Respiratory syncytial virus (RSV,
60-75%) is the most frequent etiology of bronchiolitis.
Typically affecting children under age 2,
viral bronchiolitis is the leading cause of hospitalization in infants.
Viral bronchiolitis in otherwise healthy subjects is self-limited and does not require cross-sectional imaging for further evaluation.
Radiographic findings in childhood viral pneumonia include bilateral patchy areas of consolidation,
diffuse areas of air space consolidation,
lobar consolidation and interstitial disease (5).
Mycoplasma pneumonia is responsible for about 14% of all cases of hospitalized pneumonia,
and is the most common among the atypical organism (Table 2);it is an important cause of pediatric community- acquired pneumonia insensitive to typical antibiotics,
due to its lack of a cell wall,
that usually affect older children (older than 6 years; mean age,
8 - 9 years).
A new re-emerging disease in recent years in measles pneumonia,
due to the lower vaccination.
Bacterial pneumonia are the most common among the hospitalized ones.
The most frequently respondable bacterial agents of pneumonia are shown in Table 3.
One million children develop tuberculosis disease each year,
and 210,000 die from complications of tuberculosis.
Primary tuberculosis occurs most
commonly in children and immunocompromised patients,
and pleural effusion (6).Child hood tuberculosis is very different from adult tuberculosis in epidemiology,
clinical and radiographic presentation,
and treatment: it is usually a complication of the pathophysiologic events surrounding the initial infection.
The chest radiograph typically is “sicker” than the child.
Infants are more likely to experience signs and symptoms,
probably because of their small airway diameters relative to the parenchymal and lymph node changes in primary tuberculosis.
Fungal infections of the lungs are relatively common and potentially life-threatening conditions in immunocompromised children: are mainly represented by Pneumocystis jirovecii pneumonia in patients with T-cell deficiency (mainly severe combined immunodeficiency) or aspergillosis in patients with deficit of the granulocyte function (chronic granu- lomatous disease)
Invasive pulmonary aspergillosis (IPA) is an aggressive,
opportunistic fungal infection that affects immune-suppressed children and adults.
Caused by inhalation of spores from a ubiquitous environmental mold,
IPA is most common in neutropenic patients,
especially those with immunodeficiency,
or prior stem cell transplant.
The role of imaging in children with lung mycosis is to delineate the extension of pulmonary involvement,
to assess response to therapy,
and to monitor for adverse sequelae such as bronchiectasis and cavitation.
CT is the most sensitive imaging modality for the detection of IPA,
and improved survival rates have been documented when CT leads to early detection and prompt antifungal therapy.
Especially in invasive pulmonary aspergillosis,
imaging findings – although not pathognomonic – can suggest the infection and can vary according to the immune status of the patient.
in many other cases,
imaging findings are aspecific and further diagnostic tools,
such as bronchoalveolar lavage,
immunoassays and biopsy,
can be required to make a definite diagnosis (7).
The etiologies of micotic pneumonia are show in Table 4.
the most common causes of community acquired-pneumonia (CAP) vary by age group as shown in Table 5.