[Reactive histiocytosis variant of tuberculous lymphadenitis]

Paraffin blocks from 38 cases with superficial lymph nodes exhibiting reactive histiocytosis with debris-like necrosis and neutrophil infiltration were studied by means of polymerase chain reaction for amplifying the repetitive DNA sequence (123pb fragment) specific for mycobacterium tuberculosis (M.TB-PCR), BCG immunohistochemistry (BCG-IHC) as well as acid fast stain (AF) for M.TB/MOTT (mycobacterium other than tuberculosis). The comprehensive positive rate of the three methods was 52.6% (20/38 cases) and the separate positive rates for M.TB-PCR, BCG-IHC and AF being 50%, 26% and 0.8% respectively. The results prove that (1) half of the reactive histiocytosis of lymph nodes selected in this paper are related to tuberculosis infection, i.e., some tuberculous lymphadenitis may appear as a variant of reactive histiocytosis; and (2) PCR technique is a very valuable method for making the etiologic diagnosis of tuberculous lymphadenitis.