This Publication Is Searchable The Merck Manual of Diagnosis and Therapy Section 6. Pulmonary Disorders Chapter 78. Pneumonia Lymphocytic Interstitial Pneumonitis Langerhans' Cell Granulomatosis Idiopathic Pulmonary Hemosiderosis Desquamative Interstitial Pneumonia Chronic lung inflammation characterized by mononuclear cell infiltration of the airspaces. It affects cigarette smokers in their 30s or 40s.
Most patients present with dyspnea.
There is mild to moderate alveolar septal widening by fibrous tissue, with moderate infiltration of the interstitium by lymphocytes, plasma cells, and occasionally eosinophils. The alveolar walls are lined with plump cuboidal pneumocytes. The most striking feature is the presence of numerous macrophages in most of the distal airspaces. Pulmonary function tests show a restrictive pattern with reduced DL CO , and arterial blood gases show hypoxemia. HRCT shows patchy, subpleural ground-glass opacities.