RADIOLOGY OF THE MONTH: Pulmonary Langerhans Cell Histiocytosis (PLCH).

PURPOSE: Obtaining a tissue sample diagnostic of pulmonary Langerhans cell histiocytosis (PLCH) by transbronchial biopsy is notoriously difficult. The condition's appearance on computed tomography is well described and singularly characteristic, perhaps adequate for definitive diagnosis. We propose an approach to diagnosis of these patients. METHODS: Radiology case report of PLCH in a middle-aged female smoker with two week history of nonproductive cough, low grade fevers, and fatigue. RESULTS: Computed tomography (CT) provided the diagnosis of PLCH. Transbronchial biopsies failed to provide a definitive diagnosis. CONCLUSIONS: Utility of transbronchial biopsy in diagnosis of PLCH is limited. Patients who present with signs, symptoms and high resolution computed tomography typical of PLCH do not require a correlation by tissue diagnosis. If cancer is suspected, a wedge biopsy should be performed for tissue diagnosis.

Lower airway colonization and inflammatory response in COPD: a focus on Haemophilus influenzae.

Bacterial infection of the lower respiratory tract in chronic obstructive pulmonary disease (COPD) patients is common both in stable patients and during acute exacerbations. The most frequent bacteria detected in COPD patients is Haemophilus influenzae, and it appears this organism is uniquely adapted to exploit immune deficiencies associated with COPD and to establish persistent infection in the lower respiratory tract. The presence of bacteria in the lower respiratory tract in stable COPD is termed colonization; however, there is increasing evidence that this is not an innocuous phenomenon but is associated with airway inflammation, increased symptoms, and increased risk for exacerbations. In this review, we discuss host immunity that offers protection against H. influenzae and how disturbance of these mechanisms, combined with pathogen mechanisms of immune evasion, promote persistence of H. influenzae in the lower airways in COPD. In addition, we examine the role of H. influenzae in COPD exacerbations, as well as interactions between H. influenzae and respiratory virus infections, and review the role of treatments and their effect on COPD outcomes. This review focuses predominantly on data derived from human studies but will refer to animal studies where they contribute to understanding the disease in humans.