Erythema Nodosum: A Possible Criterion for Diagnosing Acute Rheumatic Fever

The clinical features of acute rheumatic fever (ARF) are mainly the results of post-streptococcal mimicry. One of the major criteria to diagnose ARF is erythema marginatum. However, the involvement of erythema nodosum has not been reported yet. A middle-aged woman without comorbidities or addiction presented with breathlessness (NYHA-II) of 1 year’s duration with acute exacerbation in the preceding 7 days with fever, dry coughs, bilateral chest pain, orthopnea, paroxysmal nocturnal dyspnea, palpitations, bilateral leg swellings, and multiple tender faint red maculopapular rashes over bilateral shins and posterior ankle regions. Two-dimensional echocardiography confirmed rheumatic heart disease (RHD) and showed mild mitral stenosis, mild-to-moderate mitral regurgitation, severe tricuspid regurgitation, moderate pulmonary arterial hypertension, and an approximate left ventricular ejection fraction of 60%. A skin lesion biopsy showed chronic inflammatory lesions, suggesting erythema nodosum. The patient’s antistreptolysin O (ASO) titer was elevated, suggesting a prior streptococcal infection. Most of the major clinical criteria of ARF are the consequence of the molecular mimicry of Streptococci, especially such skin manifestations as erythema marginatum and subcutaneous nodules. Therefore, erythema nodosum, which also manifests itself as a delayed hypersensitivity reaction to Streptococci, can be considered a major criterion for diagnosing ARF/RHD.