Differential Diagnosis for a Palpable Lymph Node

When a lymph node is palpable, it indicates a potential underlying condition that requires careful consideration. The differential diagnosis can be categorized as follows:

• Single Most Likely Diagnosis
  • Reactive Lymphadenopathy: This is the most common cause of a palpable lymph node, often resulting from a viral or bacterial infection, which leads to the lymph node becoming enlarged as it responds to the infection.
• Other Likely Diagnoses
  • Infectious Mononucleosis: Caused by the Epstein-Barr virus, this condition often presents with lymphadenopathy, fever, and fatigue.
  • Tuberculosis: Although less common in some regions, tuberculosis can cause lymphadenopathy, particularly in the cervical or supraclavicular regions.
  • Lymphoma: Both Hodgkin and non-Hodgkin lymphoma can present with lymphadenopathy, which may be the initial symptom that prompts medical evaluation.
• Do Not Miss Diagnoses
  • Metastatic Cancer: Lymphadenopathy can be a sign of metastasis from various cancers, such as breast, lung, or melanoma. Missing this diagnosis could significantly impact treatment and prognosis.
  • HIV Infection: Acute HIV infection can cause lymphadenopathy, and early diagnosis is crucial for managing the disease and preventing long-term complications.
  • Cat-Scratch Disease: Caused by Bartonella henselae, this infection can lead to lymphadenopathy, typically after a cat scratch or bite.
• Rare Diagnoses
  • Sarcoidosis: A systemic granulomatous disease that can cause lymphadenopathy, among other symptoms like skin lesions and pulmonary findings.
  • Kikuchi Disease: A rare form of lymphadenitis, more common in young women, characterized by cervical lymphadenopathy and fever.
  • Castleman Disease: A rare disorder that involves an overgrowth of cells in the lymphatic system, which can cause lymphadenopathy.

Each of these diagnoses has distinct implications for patient management and outcome, emphasizing the importance of a thorough diagnostic evaluation when a palpable lymph node is identified.