Differential Diagnosis for a 30-year-old with a Painful, Swollen Left Lymph Node
Single Most Likely Diagnosis
- Viral or Bacterial Lymphadenitis: This is the most common cause of a swollen and painful lymph node in a young adult. The patient's symptoms, such as a swollen and painful lymph node, are consistent with an infectious etiology. The fact that the patient is not systemically ill suggests a localized infection.
Other Likely Diagnoses
- Cat Scratch Disease: Caused by Bartonella henselae, this infection typically presents with a painful lymph node near the site of a cat scratch or bite. The patient's age and the presence of a painful lymph node make this a plausible diagnosis.
- Mononucleosis: Although the patient is not systemically ill, infectious mononucleosis (caused by Epstein-Barr virus) can present with lymphadenopathy, which may be painful. This diagnosis is less likely given the lack of systemic symptoms but remains a consideration.
- Dental or Periodontal Infection: A localized infection in the mouth can cause lymphadenopathy, particularly if the infection is severe or has spread. The proximity of the lymph node to the jaw and neck makes this a possible diagnosis.
Do Not Miss Diagnoses
- Lymphoma: Although less common, lymphoma (such as Hodgkin lymphoma or non-Hodgkin lymphoma) can present with lymphadenopathy. It is crucial to consider this diagnosis, especially if the lymph node does not resolve with conservative management or if other systemic symptoms develop.
- Tuberculosis (TB): TB can cause lymphadenitis, and it is essential to consider this diagnosis, especially if the patient has been exposed to TB or has risk factors for TB (e.g., immunocompromised state, recent travel to or from a country with high TB prevalence).
- Metastatic Cancer: In rare cases, a swollen lymph node can be the first sign of a metastatic cancer. Although this is less likely in a young adult without a known primary cancer, it is a diagnosis that should not be missed.
Rare Diagnoses
- Sarcoidosis: This autoimmune disease can cause lymphadenopathy, among other symptoms. It is less common and typically presents with systemic symptoms, but it should be considered if other diagnoses are ruled out.
- Kikuchi-Fujimoto Disease: A rare, self-limiting condition that causes lymphadenitis, typically in young women. It is characterized by painful lymphadenopathy, often without systemic symptoms.
- Kimura Disease: A rare, chronic inflammatory disorder that can cause lymphadenopathy and eosinophilia. It is more common in Asian males but can occur in anyone.
Treatment
The treatment will depend on the underlying diagnosis. For viral or bacterial lymphadenitis, treatment may include antibiotics if a bacterial cause is suspected or identified, and supportive care for viral causes. For other diagnoses, treatment will be specific to the condition (e.g., antiviral medications for mononucleosis, anti-tubercular therapy for TB, chemotherapy or radiation for lymphoma or metastatic cancer).