Metabolic and inherited connective tissue disorders involving the lung

Introduction Lung involvement presenting in the course of metabolic disorders is usually overshadowed by features of the underlying disease. Pulmonary involvement is rarely the initial presenting feature. This constitutes a diagnostic challenge, particularly in adults, since the changes on biopsy are frequently nonspecific and a diagnosis of metabolic lung disease may not be considered. The pulmonary pathologist needs to be aware of the repertoire of lung pathology in these diseases to facilitate early diagnosis. This is ever more important, not only for genetic counseling but also for prompt therapy. Lysosomal storage diseases Lysosomal storage diseases constitute a group of inherited disorders characterized by lack of a protein essential for normal lysosomal function. As a consequence, substrate accumulates in cells of various organs. Marked phenotypic heterogeneity characterizes many of these diseases with regard to age of onset, severity of symptoms and organs affected including the central nervous system (CNS). In many metabolic diseases the lungs are involved and in some cases the pulmonary involvement is significant. These usually present with interstitial infiltration, airways obstruction or pulmonary hypertension.