Acid fast bacilli within histiocytes - in a lymph node from AIDS patient; tuberculous or non-tuberculous mycobacteria (MAC).
this is a Ziehl-Neelsen stain, there are Langhans' cells and the patient has AIDS--> I agree with the "mycobacteria-hypothesis", most probably MAC (opportunistic pathogens)
Answer : Mycobacterium Avium Intracellulare Complex. Acid Fast Bacilli are seen within Histiocytes ( Ziehl Neelsen Stain is used ).