Pulmonary Infiltration and Fibrosis of Unknown Etiology

Introduction  The significance of roentgenographically unchanging pulmonary lesions, in the absence of bacteriologic or pathologic proof of etiology, is difficult to determine.¹ It has been shown by Britten^2,3 that many such cases subsequently develop tuberculosis. The problem of the diagnosis of these cases is of special importance to the Armed Forces where intimate environmental situations exist. It therefore became necessary to assess accurately the risk of such persons developing active pulmonary tuberculosis and thereby becoming sources of infection. The purpose of this study was to measure the risk among military personnel retained on active duty after clinical study had rendered diagnoses of "infiltration, pulmonary, cause undetermined" or "fibrosis, pulmonary, cause undetermined." These two diagnoses were established in 1948 by a Joint Armed Forces decision⁴ in order to afford an orderly classification of unchanging, predominantly noncalcified pulmonary lesions of unknown etiology.

Material—Selection and Sources  A study group consisting of personnel with the above diagnoses and