Lymphadenopathy may be due to a number of causes including those listed below:
HIV itself. (It is however not a bad prognostic sign.)
Mycobacterium tuberculosis infection.
Kaposi's Sarcoma, or lymphomas.
Other causes e.g. pyogenic bacterial infection
Aspirate the node with a 21G needle and stain the aspirate for acid-fast bacilli (AFB).
Lymph node biopsy for histological diagnosis.
FBP and ESR