Mycobacterrek tuberculosis in the aetiology of sarcoidosis

Abstract

To summarize the general view 1 have tried to put forward on the aetiology of sarcoidosis: 1. Free discussion of aetiology demands a descriptive definition based upon morbid histology. 2. Such a definition will include some cases in which there is good evidence that sarcoidosis is a manifestation of tuberculous infection. The evidence for this in my series of 230 cases consists in the finding of tubercle bacilli in the sarcoid phase in 18; in preceding caseating tuberculosis in 11; and in the change from a sarcoid to a caseating phase, with the appearance of tubercle bacilli, in 5. 3. Indirect evidence leads me to the tentative opinion that most of the cases of sarcoidosis I see in England are of the same aetiological group. The evidence for this is their similarity to those in which direct evidence was obtained; the impossibility of detecting any clear distinction between indolent tuberculosis with low tuberculin sensitivity and sarcoidosis; and the similar distribution of reactions to graded doses of tuberculin in those patients with sarcoidosis who have and have not detectable direct evidence of present or past infection with M. tuberculosis. 4. The objection that M. tuberculosis cannot be aetiologically related to sarcoidosis because sarcoidosis does not respond to antituberculosis drugs and may be suppressed by corticosteroids is met by the observation that some, admittedly very rare, cases of undoubted tuberculosis behave in the same way in relation to these agents. 5. The cause of sarcoidosis must be sought as much in the altered reactivity of the host as in external causative agents. 6. There may well be other agents, known and as yet unknown, besides the tubercle bacillus which can cause sarcoidosis in a susceptible individual. If such a multiplicity of agents exists, the proportion of cases of sarcoidosis associated with each of them may be expected to vary from one part of the world to another. Hence statements about aetiological agents in sarcoidosis can be accepted as valid only for the population from which the cases on which they are based are derived. © 1960, British Medical Journal Publishing Group. All rights reserved.