Lymph node pathology in infectious diseases

Lymph node biopsy is usually undertaken to investigate possible neoplastic involvement and it is appropriate that most emphasis in the teaching of lymph node pathology is placed on recognizing neoplastic diseases correctly. However, it is important also to recognize the suggestive and sometimes specific changes that occur in lymph nodes due to infection. A number of fairly standard reactive patterns involving different lymphoid and stromal components within nodes can be recognized, and different combinations can suggest specific infectious causes. It remains challenging to confirm the presence of organisms in many cases of infective lymphadenopathy and therefore recommendation of additional clinical, serological and microbiological investigations, in response to recognition of suggestive pathology, is essential. In this review, we describe the typical lymph node histological features associated with relatively common infectious agents. We have not aimed to address exotica and our coverage is not exhaustive. We discuss how the causative organisms and the effects of infection in lymph nodes may differ between individuals with intact immunity and those who are immunocompromised.