The Pathology of Rheumatic Fever

ONE of the most important steps in establishing the aetiology of any given disease is the production of similar specific lesions experimentally. In the case of rheumatic fever the precise causation has not yet been clearly shown, and preparatory to some experimental observations, it was decided to examine in some detail the lesions found in this condition. In the early days the presence of rheumatic fever was recognised by the occurrence of small vegetations on the valves of the heart, accompanied sometimes by myocarditis and pericarditis. The association of acute rheumatism with a specific pathological lesion was first described by Aschoff in 1904, who observed that small nodules composed of large histiocytic cells occurred in the vicinity of the coronary arterioles. These have since been calledl Aschoff nodules, and their presence in the heart is the hallmark of active rheumatic infection. Their distribution is widespread, occurring in the valves, the endocardium, the interstitial and septal connective tissue of the myocardium, and in the pericardium. More recent observations on the pathology of rheumatic fever suggest that although the Aschoff nodule is essentially the specific lesion of rheumatism, there are other less commonly recognised lesions which, though not specific in themselves, mav be regarde(d as such vhen accompanied by Aschoff nodules. Attention has been drawin to the occurrence of rheumatic arteritis, aortitis, rheumatic pneumonia an(d nephritis, and the conception is growing that rheumatic fever is a disease process which may have widespread visceral manifestations. Pappenheimer and Von Glahn (1926) described lesions of the peripheral blood vessels in ten out of forty-seven cases of acute rheumatism, while Friedberg and Gross (1934) noted in several cases extensive involvement of the arterial system resembling polyarteritis nodosa. Eighteen cases of acute rheumatic fever and eighteen cases of mitral stenosis were available for study, and an examination of these was undertaken, first of all to analyse the structure, evolution, and distribution of the Aschoff nodule in the heart; secondly, to observe the degree of involvement of the coronary arteries, and lastly to decide, by an examination of all the organs from these cases, in what measure the pathological findings afford evidence that rheumatic fever is not only a disease of the heart, but of the whole vascular system. Since the cases available presented considerable variation in the clinical duration of the disease, there was accordingly great variation in the histological picture, and it became possible, by correlating the morphological findings with the duration of the symptoms, to trace the stages in the evolution of the specific rheumatic lesion.