Objective: To determine the prevalence and the characteristics of Mycoplasma pneumoniae-related community-acquired pneumonia (CAP) and parapneumonic pleural effusion (PPE) in children and adolescents. Methods: This was a retrospective observational study involving 121 patients with CAP/PPE hospitalized in a tertiary referral hospital between 2000 and 2008, divided into six groups according to the etiologic agent (G1 to G6, respectively): M. pneumoniae with or without co-infection, in 44 patients (group 1); etiologic agents other than M. pneumoniae, in 77 (group 2); M. pneumoniae without co-infection, in 34 (group 3); Streptococcus pneumoniae, in 36 (group 4); Staphylococcus aureus, in 31 (group 5); and M. pneumoniae/S. pneumoniae co-infection, in 9 (group 6). Results: In comparison with group 2, group 1 showed higher frequencies of females, dry cough, and previous use of beta-lactam antibiotics; longer duration of symptoms prior to admission; and lower frequencies of use of mechanical ventilation and chest tube drainage. In comparison with groups 4 and 5, group 3 showed higher frequencies of previous use of beta-lactam antibiotics and dry cough; longer duration of symptoms prior to admission; a lower frequency of use of chest tube drainage; a higher mean age and a lower frequency of nausea/vomiting (versus group 4 only); and a lower frequency of use of mechanical ventilation (versus group 5 only). M. pneumoniae/S. pneumoniae co-infection increased the duration of symptoms prior to admission. Conclusions: In this sample, the prevalence of M. pneumoniae-related CAP/PPE was 12.75%. Although the disease was milder than that caused by other microorganisms, its course was longer. Our data suggest that M. pneumoniae-related CAP/PPE in children and adolescents should be more thoroughly investigated in Brazil.

Keywords: Pleural effusion; Empyema, pleural; Pneumonia; Mycoplasma pneumoniae.

Objective: The aim of this study was to examine the parenchymal and extracellular matrix remodeling process in two histologic patterns-nonspecific interstitial pneumonia (NSIP) and usual interstitial pneumonia (UIP)-in cases of idiopathic and sclerosis/systemic sclerosis (SSc)-associated interstitial pneumonia. Methods: We examined 15 cases of idiopathic NSIP, 10 cases of idiopathic UIP, 5 cases of SSc-UIP and 9 cases of SSc-NSIP. In the lung parenchyma, epithelial cells, endothelial cells and myofibroblasts were evaluated by immunohistochemical staining, whereas histochemical staining was used in order to evaluate collagen/elastic fibers in the extracellular matrix. Results: The percentage of surfactant protein A-positive epithelial cells was significantly greater in idiopathic NSIP than in SSc-NSIP, as well as being greater in idiopathic UIP than in SSc-UIP. Idiopathic NSIP and idiopathic UIP presented significantly higher immunoexpression of alpha smooth muscle actin in myofibroblasts than did SSc-NSIP and SSc-UIP. The percentage of CD34 endothelial cells in the pulmonary microvasculature was significant lower in idiopathic UIP than in SSc-UIP. The density of collagen fibers was significantly greater in idiopathic NSIP and idiopathic UIP than in SSc-NSIP and UIP. In contrast, the elastic fiber density was significantly lower in idiopathic UIP than in SSc-UIP. Conclusions: Increased collagen synthesis, destruction of elastic fibers, high myofibroblast proliferation and poor microvascularization might represent a remodeling process found in idiopathic interstitial pneumonia, whereas the reverse might represent a repair process in SSc-associated interstitial pneumonia.

Keywords: Epithelial cells; Neovascularization, pathologic; Collagen; Elastin; Idiopathic interstitial pneumonias; Scleroderma, systemic.