[Histopathology of the Mitsuda reaction in healthy adults not in contact with Hansen's disease patients].

A detailed study on the histopathology of Mitsuda's reaction was made in 100 adult non-contact hanseniasis patients inoculated with lepromin A (armadillo). It was found that the histological structure of Mitsuda's reaction with lepromin A does not differ from the one observed with lepromin H. There is also no difference between the histological picture observed in healthy non-contacts and the one found in tuberculoid patients and in contact healthy persons. Mitsuda's reaction in non-contact hanseniasis patients presented variations of histological degree--Classes O (-) I (+/-) II (+) III (++) IV ( )--from no inflammatory reaction and positive bacilli, until formation of a complete tuberculoid granuloma and absence of bacilli. In 97% of the cases reaction was positive. Class III, i.e., represented by incomplete tuberculoid granuloma formed by epithelioid cells with follicular arrangement and lymphocytic halo, predominated in the series (42%). The findings of this research state, once again, that an efficient result of the Mitsuda's reaction depends fundamentally of the histological examination, since in only 16 cases the clinical reading coincided with histopathology. Disaccordance found on the remaining 84 cases was attributed to the secondary alterations (necrosis and suppuration) associated to the histological structure of the Mitsuda reaction follows the Jadassohn-Lewandowsky law and are in accordance with the morphological concept and classification of polar granulomas proposed by Michalany & Michalany.