Differential Diagnosis for Lymphadenopathy
- Single most likely diagnosis
- Recurrent group A streptococcal infection: This is the most likely cause given the patient's history of similar symptoms and lymphadenopathy that resolved with empiric antibiotic therapy. The patient's presentation of sore throat, malaise, and cervical lymphadenopathy, which improved with time, is consistent with recurrent streptococcal infections.
- Other Likely diagnoses
- Epstein-Barr virus infection: Although the patient's symptoms and lymphadenopathy could suggest infectious mononucleosis, the lack of fever, fatigue, and the negative monospot test (not explicitly mentioned but implied by the negative workup) make this less likely. However, it remains a consideration given the patient's age and presentation.
- Atypical mycobacterial infection: This could be a consideration, especially in immunocompromised patients or those with a history of smoking. However, the resolution of symptoms without specific treatment for mycobacterial infection makes this less likely.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Lymphoid lineage neoplasm: Although the patient's lymphadenopathy has been recurrent and resolves with antibiotic therapy, lymphoma must be considered, especially given the patient's history of hepatitis C, which increases the risk of lymphoproliferative disorders. The lack of systemic symptoms (e.g., weight loss, night sweats) and the unremarkable CBC with peripheral smear decrease the likelihood but do not rule it out entirely.
- Hepatitis C-related vasculitis: Given the patient's history of hepatitis C, there is a possibility, albeit small, of hepatitis C-related vasculitis or cryoglobulinemia, which could cause lymphadenopathy. However, the absence of other systemic symptoms (e.g., skin rash, kidney issues) makes this less likely.
- Rare diagnoses
- Other rare infections or autoimmune conditions could potentially cause lymphadenopathy but are less likely given the patient's presentation and the information provided. These would include conditions such as Castleman disease, Kikuchi-Fujimoto disease, or sarcoidosis, among others. The patient's symptoms and response to empiric treatment do not strongly suggest these diagnoses, but they could be considered if more common causes are ruled out.