[A study of the histopathological characteristics of nontuberculous mycobacteria lymphadenitis].

Objective: To describe the distinctive histopathological changes of nontuberculous mycobacteria lymphadenitis.

Methods: An experimental animal model of nontuberculous mycobacteria lymphadenitis was established and the histopathological changes were observed by light microscope. The paraffin imbedded tissue samples from patients suspected of having lymphoid tuberculosis were also detected by triplex polymerase chain reaction and studied by light microscope.

Results: The distinctive histopathological changes of nontuberculous mycobacteria lymphadenitis in the animal model were as follows: (1) Tubercular granuloma formation in lymph nodes which were infected with nontuberculous mycobacteria. Coagulation necrosis was located at the center of the granuloma, and the necrosis looked different from the caseation necrosis caused by mycobacterium tuberculosis. Many neutrophils and their nuclear debris were distributed over the necrosis area. Surrounding the central necrosis area, many epithelioid cells, lymph cells and mononuclear cells could be found. The periphery of the granuloma was surrounded by fibrous tissues. Langhans giant cells could be found in the granuloma and outside the granuloma, while these cells were usually found only in the granuloma of tuberculosis. (2) Serpiginous necrosis was found in the lymph nodes infected with nontuberculous mycobacteria. Many neutrophils and their nuclear debris were distributed over the necrosis area. Around the central necrosis area, many epithelioid cells, lymph cells and mononuclear cells could be found. The fibrous tissues were in the borderline. (3) Star-like necrosis and aristiform necrosis were also found in lymph nodes infected with nontuberculous mycobacteria. A paraffin imbedded tissue sample was detected by triplex polymerase chain reaction and the diagnosis of nontuberculous mycobacteria lymphadenitis was made. In this sample, epithelioid granuloma, serpiginous necrosis and star-like necrosis were found. Neutrophils and their nuclear debris were found distributed over the necrosis area, while epithelioid cells, lymph cells, mononuclear cells and Langhans giant cells were found around the central necrosis area. Polar arrangement of the nuclei of epithelioid cells was evident. The lesion was surrounded by fibrous and collagen tissues.

Conclusion: Serpiginous, star-like and aristiform necrosis were the distinctive histopathological changes of nontuberculous mycobacteria lymphadenitis. Neutrophils and their nuclear debris were abundant over the necrosis area. Polar arrangement of the nuclei of epithelioid cells was also a distinctive histopathological manifestation.