From the Research
The most appropriate test to order now is a throat culture (option B). This patient presents with symptoms and signs consistent with erythema nodosum, characterized by painful erythematous nodules on the anterior lower legs, which is often a reactive process to an underlying condition. Given his recent febrile illness with sore throat that hasn't completely resolved, along with current findings of tonsillar edema and cervical lymphadenopathy, a Group A Streptococcal pharyngitis (strep throat) is the most likely underlying cause. Streptococcal infections are a common trigger for erythema nodosum. The elevated C-reactive protein (4.3) further supports an inflammatory or infectious process. A throat culture would help confirm this diagnosis and guide appropriate antibiotic therapy, typically penicillin or amoxicillin for 10 days if positive, as recommended by the most recent guidelines 1. While the Monospot test could be considered for Epstein-Barr virus, the clinical picture more strongly suggests streptococcal infection. A skin biopsy would be invasive and unnecessary at this point, and serum ACE levels would be more appropriate if sarcoidosis were suspected, which is less likely given the clinical presentation. The use of throat culture is supported by studies such as 2, 3, and 4, which highlight its importance in diagnosing group A beta-hemolytic streptococcal pharyngitis. More recent reviews, like 5, also emphasize the role of throat culture in the diagnosis of strep throat, alongside other diagnostic methods and clinical guidelines for treatment.
The clinical presentation of this patient, including the recent febrile illness, sore throat, tonsillar edema, and cervical lymphadenopathy, aligns with the criteria for suspecting streptococcal pharyngitis, as discussed in 1 and 5. The recommendation for a throat culture is based on the highest quality and most recent evidence available, prioritizing the diagnosis and appropriate treatment of the underlying cause of erythema nodosum in this patient.
Key points to consider in this case include:
- The patient's symptoms and signs are consistent with erythema nodosum and streptococcal pharyngitis.
- The elevated C-reactive protein supports an inflammatory or infectious process.
- Throat culture is the diagnostic standard for streptococcal pharyngitis, as highlighted in 1, 2, and 4.
- Appropriate antibiotic therapy, such as penicillin or amoxicillin, can be guided by the results of the throat culture.
- Other tests, like the Monospot test for Epstein-Barr virus, are less relevant given the clinical picture suggesting streptococcal infection.