Bacterial (Suppurative) Lymphadenitis

Abstract

Acute lymphadenitis is caused by bacterial infection. Opportunistic bacterial infections can involve regional lymph nodes and lead to acute lymphadenitis that may become suppurative. Infections are often caused by Staphylococcus aureus and, less often, group A streptococcus.

Involved lymph nodes may or may not be enlarged. In early phases of bacterial lymphadenitis, the nodal architecture is intact and sinuses are distended by a pale eosinophilic proteinaceous fluid with numerous admixed neutrophils and macrophages (sinus catarrh). Neutrophils eventually form microabscesses that may enlarge and coalesce to form suppurative lymphadenitis leading to abscess formation or a draining sinus. Bacterial colonies may be seen on histologic sections. As the acute inflammatory phase subsides, the inflammatory infiltrate becomes richer in lymphocytes, plasma cells, and debris-laden macrophages.