Essentially 5 broad etiologic categories lead to lymph node enlargement.
1. An immune response to infective agents (eg, bacteria, virus, fungus)
2. Inflammatory cells in infections involving the lymph node
3. Infiltration of neoplastic cells carried to the node by lymphatic or blood circulation (metastasis)
4. Localized neoplastic proliferation of lymphocytes or macrophages (eg, leukemia, lymphoma)
5. Infiltration of macrophages filled with metabolite deposits (eg, storage disorders)
**Infections**
Infectious mononucleosis.
Cytomegalovirus may cause a syndrome similar to infectious mononucleosis.
TB: In a child with tuberculosis, generalized lymphadenopathy may indicate hematogenous spread of tubercle bacilli.
Brucellosis may accompany chronic or intermittent lymphadenopathy.
Salmonella infection can correspond to generalized adenopathy.
Tularemia may be accompanied by regional or generalized adenopathy, most commonly cervical, with local tenderness, pain, and fever.
Bubonic plague is caused by Y pestis.
**Immunologic or connective tissue disorders**
Juvenile rheumatoid arthritis should be considered in unexplained fever and persistent lymphadenopathy in a child.
Serum sickness can correspond with generalized tender lymphadenopathy.
Chronic graft versus host disease.
**Primary disease of lymphoid or reticuloendothelial tissue**
Acute leukemia
Hodgkin disease
Non-Hodgkin lymphoma
Lymphosarcoma
Nonendemic Burkitt tumor
Nasopharyngeal rhabdomyosarcoma
Neuroblastoma
Reticulum cell sarcoma
Malignant histocytosis or histocytic lymphoma
Thyroid carcinoma, chronic lymphocytic thyroiditis
Histiocytosis X
Benign sinus histiocytosis
Angioimmunoblastic or immunoblastic lymphadenopathy
Chronic pseudolymphomatous lymphadenopathy (chronic benign lymphadenopathy)
**Immunodeficiency syndromes**
Acquired immunodeficiency syndrome
Chronic granulomatous disease of childhood
Hyperimmunoglobulin E (Job) syndrome
