In the normal host, RSV, adenovirus, Mycoplasma and pneumococcus are common. Tuberculosis, once thought to be almost irradicated in normal children in the United States, is making a come back, especially among newly arrived immigrants and the poor who are exposed to overcrowded conditions, poor sanitation, inadequate nutrition, and exposure to contagious adults as the source of infection. In AIDS patients, diffusely disseminated reticulo-nodular interstitial infiltrates can be due to a variety of illness especially l.i.p., miliary tuberculosis., varicella, CMV, and Pseudomonas. Radiologic signs of pneumonia in children include peribronchial infiltrate, lobar segmental consolidation with air bronchograms, and air space obliteration. Regional Iymphadenopathy due to viral or bacterial pneumonia is common in children, although when disproportionate to the extent of pulmonary infiltrate, should raise the question of primary tuberculosis.
Pleural effusion tends to be less common but can accompany pneumococcal infection.
True empyema of the chest is uncommon and may require CT scan for proper diagnosis. Occasionally referred abdominal pain from a pleural based lobar pneumonia can mimic appendicitis. In the toddler age group unexplained cough especially without fever or preceding upper respiratory infection, can be a sign of an aspirated foreign body. Other clinical signs and symptoms of airway foreign bodies include choking, loss of phonation, wheezing, recurrent pneumonia, asymmetric breath sounds, and in chronic situations, hemoptysis. Since most aspirated material is radiographically non-opaque, it is usually difficult to delineate the foreign body per se unless special techniques or CT are used.