Definition and EtiologyTop
Depending on the cause, lymphadenopathy (enlarged lymph nodes) is a result of an increased number of normal or neoplastic lymphocytes, inflammatory cells, or both. In adults lymph nodes ≥1 cm in diameter are considered significantly enlarged.
1) Infections: Bacterial (tuberculosis, syphilis, staphylococcal infection, streptococcal infection, brucellosis, tularemia, diphtheria, leprosy, cat-scratch disease), viral (cytomegaly, infectious mononucleosis, HIV, herpes simplex virus, varicella-zoster virus, herpes zoster virus, rubella, measles, viral hepatitis), protozoal (toxoplasmosis), fungal (histoplasmosis, coccidiomycosis, blastomycosis, sporotrichosis, torulosis), rickettsiosis.
2) Immunologic diseases: Systemic lupus erythematosus, rheumatoid arthritis, mixed connective tissue disease, dermatomyositis, Sjögren syndrome, serum sickness, drug hypersensitivity reactions (phenytoin, hydralazine, primidone, gold salts, carbamazepine), primary biliary cholangitis, graft-versus-host disease.
3) Tumors: Primary tumors of the lymphopoietic system (Hodgkin lymphoma, non-Hodgkin lymphoma, chronic lymphocytic leukemia, acute lymphoblastic leukemia), metastasis of solid tumors.
4) Storage diseases: Gaucher disease, Niemann-Pick disease, Fabry disease.
5) Other: Thyrotoxicosis, sarcoidosis, Castleman disease, Kawasaki disease, Langerhans cell histiocytosis.
After confirming lymphadenopathy in a certain area, examine all the lymph nodes accessible for palpation. Assess the lymph nodes for:
1) Location: Localized lymphadenopathy (limited to one group of lymph nodes) suggests a local cause (exceptions are the following systemic disorders: tularemia, yersiniosis, non-Hodgkin lymphoma), while generalized lymphadenopathy suggests systemic disease, including malignancy of the lymphatic system.
2) Texture: Firm lymph nodes suggest metastases, lymphoma, or chronic lymphocytic leukemia. Relatively soft lymph nodes are found in acute leukemia. Soft lymph nodes, sometimes fluctuant, are found in tuberculosis, acute lymphadenitis, and diphtheria (fistulas communicating with the skin may be present).
3) Tenderness: Pain on palpation suggests rapidly progressive enlargement, typical of inflammation; less frequently, it may be associated with bleeding to the lymph node, immune reaction, or malignancy.
4) Mobility of the lymph node relative to the skin and surrounding tissues: Fixed lymph nodes and conglomerates of lymph nodes are found in patients with chronic inflammation or with malignancy.
Lymph nodes that are inaccessible to physical examination (mediastinal and retroperitoneal) can be assessed using imaging studies (radiography, ultrasonography, computed tomography [CT], magnetic resonance imaging [MRI], scintigraphy). In equivocal cases histologic examination of the lymph node is necessary and achieved through biopsy or excisional removal.