Pulmonary changes in collagen diseases.

In recent years there has been a great deal of interest expressed in a group of disorders referred to as “collagen diseases.” This group has been more or less separated from others by virtue of the fact that the primary anatomic change takes place in the mesodermal structural units of the body rather than in epithelial parenchyma as is the case in so many well known human afflictions.1’ 2 The designation of collagen disease has received general approval especially by the clinician, however, its shortcomings have been disturbing to many others.2’ 3, Admittedly it may foster rather careless thinking and unjustified grouping of poorly understood diseases but the serious objection lies in the fact that it does not identify the cause or fundamental nature of the disorder nor does it designate an anatomic site. Be that as it may it has served its purpose in focusing attention on heretofore unappreciated chemical and anatomic changes of supporting tissue ground substances. The fundamental disturbance in collagen diseases is an alteration of the mucopolysaccharide ground substance of mesodermal tissue.5 Histologically this is initially identified by tinctorial alterations, swelling, necrosis, disorganization, and followed almost immediately by inflammatory cellular proliferation and subsequently by repair. Changes affect the entire body for connective tissue and blood vessels are universal and do not form a collected mass or organ. The anatomic site of maximum change, degree of change, and the speed of the development of the change have allowed a separation of collagen diseases at least on clinical grounds. Histologically there is no consistent difference which might allow diagnosis of a particular disease in this group by examination of lung alone. The commonly accepted conditions include acute disseminated lupus erythematosus, rheumatic fever, polyarteritis, rheumatoid arthritis, dermatomyositis, and scleroderma. Some are willing to also include serum sickness and glomerulonephritis. Table I shows the listing of anatomic sites of principal involvement and it can readily be seen that all of these diseases are actually general body disorders. In addition to major anatomic site there is also a consideration of speed of reaction and this is tabulated in Table II.