Respiratory manifestations of systemic disease. 3. Neurologic, skeletal, dermatologic, gynecologic, and gonadal diseases and disorders of pregnancy.

Many nonpulmonary diseases may present with respiratory manifestations or may involve the lungs later in the disease course. The mechanisms by which such involvement occurs are almost as diverse as the diseases themselves and include the following. Hematogenous spread of disease is one of the most common mechanisms of lung involvement, for example, lung involvement by metastatic malignant disease. Cytotoxic factors from another anatomic location may be deposited in the alveolar basement membranes and cause pulmonary damage, for example, pulmonary hemorrhage associated with Goodpasture's syndrome. The pulmonary vasculature may prominently manifest generalized disease, as frequently occurs in Wegener's granulomatosis. Toxins accumulated as a result of disease in another organ system may damage the alveolar capillaries and result in pulmonary edema, as can occur in patients with severe azotemia due to renal failure. Depletion of lung surfactant as a consequence of disease in another organ system may produce alveolar collapse and respiratory failure; a disease that can have this effect is acute pancreatitis. The lungs may be the first organs to exhibit, through unknown mechanisms, underlying systemic diseases such as the collagenoses. Humoral factors released in another anatomic site may cause pulmonary problems; for example, bronchospasm may develop in patients with carcinoid of the intestine as a result of serotonin released by the tumor. Injury to another organ system can produce lung damage by complex mechanisms; an excellent example is the occasional development of neurogenic pulmonary edema in patients with trauma to the brain.(ABSTRACT TRUNCATED AT 250 WORDS)