Lipoids in the reactional tuberculoid leprosy granuloma, their diagnostic value.

The lepra cell, which Virchow first described and which bears his name, is the anatomic characteristic of the granuloma of lepromatous leprosy. Unna demonstrated that the vacuoles of the foamy cells of Virchow are due to fat in the cytoplasm, and not to edema as was thought by the author who saw them first. Mitsuda (4), in a paper published in 1936, claims to have stained that substance with sudan III in 1902 and, in more recent microchemical studies, to have proved that chemically it is a lipoid of unknown but possibly very complex formula. His views regarding the source of this substance will be considered later. Rath de Souza and Lecheren Alayon (6) have considered the matter of lipoids in the different lesions of leprosy, in the light of the new classification of the disease-conceived and, at _ that time (1942), accepted only by South American leprologists but lately approved, with slight modifications, by the Fifth International Leprosy Congress at Havana, in 1948-and thE!ir views will also be considered. In the present paper is reported a study of the same problem, emphasizing the differential diagnosis between lepromatous and reactional tuberculoid leprosy, which is still a problem.