TOW #45: Lymphadenopathy

This week’s topic is a review of lymphadenopathy and how to characterize those lumps and bumps that parents worry about (and us too!). Interesting fact of the day: there are about 600 lymph nodes in the body! One of the fascinating zebras on the differential for lymphadenopathy is Kikuchi disease, a necrotizing lymphadenitis, recently reviewed in an excellent morning report by R3 Josiah Peterson MD PhD.

The teaching materials for the week:

Take-home points on lymphadenopathy:

  1. What’s the definition of lymphadenopathy? Abnormality in size, number, or consistency of lymph nodes (whereas lymphadenitis is an inflammatory or infectious enlargement of lymph nodes). Lymph nodes are normally up to 1cm in the axillary and cervical regions and up to 1.5cm in the inguinal region. “Shotty lymphadenopathy” refers to multiple small, mobile lymph nodes resembling birdshot (~2mm) or buckshot (~8mm) under the skin. This is a common, self-limited finding in children under five typically during viral illnesses. Any node >2cm should be considered abnormal. Generalized lymphadenopathy refers to two or more noncontiguous sites of lymph node enlargement.
  2. Why lymph?: An “ultrafiltrate” of blood, lymph carries immune cells in lymph capillaries through the entire body except the brain and heart. The bone marrow and thymus are the primary lymphoid organs because they generate B and T lymphocytes. Secondary lymphoid organs are lymph nodes, spleen, and mucosa-associated lymphoid tissue (MALT), including the tonsils, appendix, and Peyer patches of the ileum. Because young children’s immune systems are actively developing, we commonly feel enlarged lymph nodes.
  3. What’s on the differential diagnosis? The broad categories are infectious, immune disorders, and malignancy. Under age 5, we know cervical lymph nodes are almost always infectious-don’t forget scalp and dental sources. Supraclavicular nodes are always abnormal, most commonly caused by lymphoma, mycobacterial infection, or sarcoidosis. Generalized lymph node swelling is more likely to be systemic infection (viruses, including EBV, CMV, HIV, syphilis or toxoplasmosis), but also may be a sign of malignancy or autoimmune disorders.
  4. What are key parts of history and physical exam? Ask about systemic symptoms, including fever, weight loss, night sweats, poor appetite, and fatigue. Ask about the time course, and change in the size or number of lymph nodes. Review exposure to insects, animal contacts, travel, and immunizations. Determine locations of lymph nodes, whether unilateral versus bilateral, soft versus hard, mobile versus fixed, and tender versus non-tender. Focus the rest of the exam on chief complaint/symptoms. More worrisome signs for malignancy include hard/ rubbery, immobile, persistent and non-tender lymph nodes (though malignant ones can also be tender).
  5. When should we do a work-up and what should it include? If nothing suggests malignancy, observe for 2-4 weeks, then follow-up. If not resolved, work-up would include viral serologies and CBC, ESR and CRP. Additional testing is done based on history (e.g., Bartonella henselae PCR when concerns for cat scratch, or TB testing for patients at risk). When there is concern for malignancy, including prolonged duration, location, large or increasing size, abnormal texture, and/or the presence of constitutional symptoms, we should refer for biopsy and obtain CXR to look for mediastinal lymphadenopathy.