Chapter 30: Respiratory Tract Infections & Childhood Disorders

Respiratory Tract Infections & Childhood Disorders differentiates between acute and chronic rhinosinusitis and various types of pneumonias, classifying them by acquisition setting (community- or hospital-acquired) and etiology (typical bacterial vs. atypical viral/mycoplasmal). A detailed section addresses Tuberculosis (TB), explaining the pathogenesis centered on a cell-mediated immune response, the formation of the Ghon focus and Ghon complex, and the significant global challenge posed by multidrug-resistant strains. Systemic fungal infections endemic to specific geographic regions, such as histoplasmosis, coccidioidomycosis ("valley fever"), and blastomycosis, are also explored, noting their clinical resemblance to TB. The chapter transitions to pulmonary neoplasms, identifying cigarette smoking as the primary risk factor for lung cancer, which remains the leading cause of cancer death worldwide. Lung cancers are broadly categorized into Small Cell Lung Cancers (SCLC), which are highly malignant and prone to early dissemination and paraneoplastic syndromes, and Non-Small Cell Lung Cancers (NSCLC)—including squamous cell carcinoma and adenocarcinoma—which are classified using the Tumor, Node, Metastasis (TNM) staging system. Finally, the chapter addresses pediatric respiratory disorders, highlighting the unique vulnerability of infants due to the small size of their airways and the ongoing lung development process. Specific neonatal conditions like Respiratory Distress Syndrome (RDS), caused by pulmonary immaturity and surfactant deficiency, and chronic Bronchopulmonary Dysplasia (BPD) are discussed alongside life-threatening childhood infections such as epiglottitis, which causes sudden supraglottic obstruction, and viral croup (acute laryngotracheobronchitis), known for its characteristic stridor and barking cough, contrasting them with lower airway infections like bronchiolitis, commonly caused by Respiratory Syncytial Virus (RSV).