Abstract
Among the most common infections in children are those affecting the lower respiratory tract, lower respiratory tract infections. Most frequently, this involves viral or bacterial pneumonia. Worldwide, more than two million children die of pneumonia annually, predominately in developing countries. Mortality is extremely rare in the United States and other parts of the developed world. However, respiratory infections remain a major cause of morbidity in the United States. Children experience 6–8 acute respiratory illnesses per year. Even in the most optimal circumstances, however, pediatric pneumonia is often difficult to diagnose. Patient history, physical findings, and laboratory results can all be elusive. Children with pneumonia do not necessarily present with the signs and symptoms typically associated with adult LRTI such as fever, cough, wheezing, tachypnea, and retractions. Section 11.1 of this chapter concentrates on the plain film radiographic manifestations of community-acquired lower respiratory tract illnesses in immunocompetent children who have developed beyond the neonatal period (>30 days). In Sect. 11.2, pulmonary cysts seen on plain chest radiographs as completely or partially air-filled, round masses may be of congenital, infectious/inflammatory, traumatic, or neoplastic in origin. Many of these lesions are discussed in greater detail elsewhere in the text, but are briefly discussed here in an approach to the differential diagnosis of lucent pulmonary cysts. The differential diagnosis can be refined based on the age of the patient and distribution within the lungs (unilateral vs. bilateral), as well as the clinical presentation and the presence of other findings such as nodules or wedge-shaped opacities. Section 11.3, which incorporates a conglomerate of different entities based on the common radiographic appearance of solitary or multiple pulmonary nodules, is divided into anomalies that tend to cause solitary nodules, and those that cause multiple nodules. Because developmental, infectious, inflammatory, hemorrhagic, and neoplastic disorders can all give the appearance of pulmonary nodules, many different disease entities will be touched upon or discussed in this chapter, or discussed elsewhere in this textbook in greater detail. Each section will describe the radiological or clinical traits of the various diseases characterized by pulmonary nodules. Section 11.4 discussed bleeding from the airway (hemoptysis) in childhood, which is an infrequent occurrence that represents a large array of underlying pathologies. The source of the blood is frequently in the mouth or other upper airway structure, and because cough and vomiting are often contemporaneous, gastrointestinal bleeding may be mistaken as emanating from the airway. As discussed in Sect. 11.5, there are many causes of over inflation of the lungs and increased lucency. This may affect all of both lungs, all of one lung or scattered segments of one or both lungs. These observations may be easily recognized from chest X-ray (CXR) or require dynamic imaging such as chest fluoroscopy or inspiratory/expiratory CT. As discussed in Sect. 11.6, necrotizing pneumonia (NP) is becoming an increasingly recognized complication of community-acquired pneumonia in children. NP has been recognized as a complication of pneumonia in adults for several decades, when initially described NP was thought to be extremely rare in children. The incidence of NP appears to be increasing, similar to the observed rise in cases of complicated pneumonia overall. Possible explanations for the increased incidence of NP include the emergence of particularly virulent microorganisms or simply the increased awareness and detection of this complication due to improved imaging techniques.