This paper will concern itself with differentiating between the six syndromes typically classified as collagen diseases. Other diseases with manifestations common to these will not be differentiated, or even enumerated. Ocular manifestations will be omitted.
The approximate relative incidence of these six collagen diseases is as follows:
Rheumatoid arthritis - - Rheumatic fever Lupus erythematosus - - - Periarteritis nodosa - - Dermatomyositis Scleroderma
Some Features of the Collagen Diseases as a Group
The collagen diseases are characterized by widespread focal lesions of connective tissue. They differ individually as to sites of predilection, and there are quantitative histopathological differences in the lesions. However, there is sufficient overlap that at times two or more collagen diseases appear histologically and clinically indistinguishable in their manifestations. This is more likely during early stages than later. Even more commonly, initial manifestations more or less characteristic of one collagen disease (e.g., rheumatoid arthritis) may evolve into those typical of another (e.g., lupus
GUYTON JS. Differential Diagnosis of Collagen Diseases. AMA Arch Ophthalmol. 1956;56(4):563-567. doi:10.1001/archopht.1956.00930040571005