Borderline tuberculoid leprosy

ABSTRACT

Three cases which bear on the unsettled question of the transformation of tuberculoid leprosy to the lepromatous type are presented. Two of them have been for long periods in a peculiarly unstable, "borderline" condition, repeatedly suspected of becoming lepromatous. The third one presented, in the phase here dealt with, as at one time one of the others did to a less extent, lesions of peculiar, atypical morphology and histology that are designated as "relapse tuberculoid". The persistently borderline cases have long been characterized mainly by repeated reactions of more or less mild degree and repeated, at times continuous, eruptions of papular lesions, the earlier large leprids having subsided relatively early in the course of the disease. The papular elements have usually not been discrete, but diffused peripherally, and when acute they have ordinarily yielded numerous to abundant bacilli; yet they have regularly receded spontaneously or yielded promptly to local treatment in the way of papular leprids, while the new ones appeared coincidentally or in later eruptions. Histologically most of them have been indeterminate, neither tuberculoid nor frank lepromatous. Seldom have they shown any attempt to anlarge, but that development has been seen. At one time in Case 1 a few become miniature circinate leprids, of clear-cut tuberculoid. Nor have these cases become lepromatous, though the prognosis remains uncertain. Other lesions of highly atypical, suspicious character appeared during one period in Case 2, and in the third case such lesions were extensive and very striking. With their diffused outlines, abundant bacilli and peculiar histology, they might easily be taken for lepromata; and, with enclosed or adjoining unaffected areas that are know to have been sites of previous major tuberculoid lesions, against which the infiltration is sharply limited, they might seem to have arisen by lepromatous transformation of such earlier lesions; yet they later subsided in the way of leprids. The explanation of the obvious relationship of these "relapse tuberculoid" lesions to the apparently healed, previously tuberculoid areas is a matter of speculation. There is reason to believe that such lesions have at times been taken to be lepromata, thus confusing the picture of transformation of tuberculoid cases if that occurs, which remains to be established satisfactorily...