The lepromin test in lepra reaction. II. Histology of the reaction lesions and persistence of the injected bacilli

ABSTRACT

1- Biopsy specimens of the sites of lepromin tests in two groups of leprosy patients, thirty-five lepromatous cases in lepra reaction and six nonreaction control cases (four N3 and two L3), were removed from 21 to 49 days after the test injections were made and examined histologically and for the presence of the injected bacilli in the tissues. 2- In the first, or experimental, group the reactions were three-plus, one cases; two-plus, two cases; one-plus, sixteen cases; and negative, sixteen cases. In the second, or control, group the four neural cases gave three-plus reaction, one case; and two-plus, three cases; two lepromatous cases were both negative. 3- The specimens from both cases giving the three-plus reactions (one experimental and one control) showed histological tuberculoid pictures. Of the total of five cases in both groups giving two-plus reactions, four showed histological tuberculoid pictures-an 80 percent agreement if the tuberculoid picture in the reaction lesion is to be considered the criterion for a definitely positive test. 4- Of the sixteen cases recorded as giving one-plus reactions, only three, or 19 percent, showed tuberculoid or subtuberculoid pictures, concomitantly with foreign-body tubercles. In the other thirteen, or 81 percent, the histological changes consisted only of more or less marked cellular compact masses, proliferation of connective tissue with slight or dense fibrosis and infiltrations with vacuolated large monocytes, foreign-body giant cells, or foreign-body tubercles. These changes are interpreted to be false positive or nonspecific reactions to the injected lepromin emulsion. 5- Of the total of eighteen negative reactions, in none could either the tuberculoid picture or the foreign-body tubercle be eration or from slight to dense fibrosis, with slight infiltration of large monocytes and foreign-body giant cells (nine cases), slight hypertrophy of the epidermal pegs (two cases), and vacuoles of the injected lepromin in the interstices of connective tissue without cellular reaction (one cases). In six instances no trace of the injection could be demonstrated.