Pulmonary manifestations in the diffuse collagen diseases.

The aetiology of the diffuse systemic collagen diseases, embracing rheumatoid arthritis, sclero-derma, dermato-myositis, polyarteritis nodosa, and disseminated lupus erythematosus still remains obscure. The need persists for a wider concept of their clinical picture, with less emphasis on one particular system. Ellman (1947), in respect of rheumatoid arthritis, suggested " rheu-matoid disease" as a more comprehensive designation in view of the protean clinical manifestations in certain of the more acute cases. Among the visceral manifestations of rheu-matoid disease attention has already been drawn to the coexistence of joint and lung lesions which have been regarded as hypersensitivity manifestations in the sense suggested by the work of Rich and Gregory (1943). Experience of the collagen diseases leads to the recognition of certain distinct clinical patterns, which histopathology fails to differentiate. emphasized the unity of vascular pathology evident in so wide a variety of clinically dissimilar conditions as disseminated lupus erythematosus, polyarteritis nodosa, dermato-myositis, sclero-derma, temporal arteritis, and the rheumatic diseases. This clinical nosology is founded upon the local or generalized manifestations of an apparently uniform and diffuse arteritis. The basic vascular lesion is regarded as a result of fibrinoid degeneration of the ground substance of the arterial wall, leading to progressive occlusion or to aneurysmal dilatation of the vessel wall, with secondary cellular infiltration and ischaemic fibrosis of the dependent structures or organs. postulated a unitary concept for the widely differing clinical manifestations of collagen disease, a view contested, however, by Kellgren (1952). The similarity of the histopathology of these diseases may indicate a common pathogenesis. in which the injection of histamine or of a foreign protein induced a necrotizing arteriolitis in the experimental animal, sometimes accompanied by an acute carditis with myocardial Aschoff body formation, suggest that induced vascular hyper-sensitivity leads to necrosis of the vascular wall and reactive cellular infiltration. This work lends some support to the unitary theory of the underlying pathogenesis, but fails to elucidate the identity of the aetiological factors and does not explain the curious specificity of the manifestations in so diverse a group as the clinically separated collagen disorders. The different distribution of the major lesions in these diseases suggests an undue tissue susceptibility, primarily in the structures derived from the mesenchyme or, perhaps, a genetically determined tissue reaction pattern to a common aetiological factor. The protean manifestations of the vascular lesions frequently mask the diagnosis in the early stages. The clinical findings predominating in …