Syphilitic (Luetic) Lymphadenitis: Generalized lymphadenopathy is a regular feature of secondary syphilis, whereas localized (regional) lymph node enlargement is seen with primary and some cases of latent or early tertiary syphilis. In primary syphilis, the causative agent, treponema pallidum, spreads from penile chancre through lymphatics to cause inguinal lymph node enlargement (as seen in this image). Femoral, epitrochlear, cervical or axillary lymph nodes may be involved, depending upon the location of the primary lesion. In patients who have oral lesions (the most common extragenital site in syphilis), there is enlargement of tonsils and cervical lymph nodes. Image credit: Susan Lindsley/Centers for Disease Control & Prevention, Atlanta, USA.