Nodular aggregate of fluffy macrophages are highly characteristic of MAI lymphadenitis.

The macrophages have small nuclei and abundant foamy cytoplasm.

Fite stain shows acid-fast bacilli packed in the cytoplasm of the macrophages.

Many of these cases are usually seen in the setting of AIDS, where the host cannot mount an appropriate immune response. Thus, necrotizing granulomas are not usually seen. Characteristic features of MAI lymphadenitis include a proliferation of foamy or fluffy macrophages and the presence of "red snappers" or acid-fast bacilli on special stains. Cervical node enlargement is a common presentation.

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