ABSTRACT
Background: Constrictive pericarditis associated with actinomycosis infection is a rare and challenging diagnosis due to its insidious manifestation. We describe the successful treatment of pericardial infiltration and constriction due to actinomycosis. Case summary: A 50-year-old Aboriginal man presented with insidious onset of fatigue, dyspnoea, pleuritic chest pain, fever, drenching sweats, severe exercise intolerance to 50â m, and recurrent itchy skin lesions over 8 months. Prior investigations, including serial fluorodeoxyglucose (FDG)-Positron emission tomography scans, found a progressively enlarging, metabolically active anterior mediastinal mass with two biopsies on separate occasions showing no malignancy, granulomas, tuberculosis, or other pathology. Screening for infective, autoimmune, and connective tissue disease was negative. A transthoracic echocardiogram (TTE) showed fibrinous pericarditis with extensive myocardial tethering and constrictive physiology confirmed on heart catheterization. A pericardial biopsy showed inflammatory tissue only. Biopsy of a skin lesion on the buttock showed abscess formation with Splendore Hoeppli phenomenon with Gram-positive and Grocott-positive filamentous bacteria suggestive of actinomyces, confirmed by 16S rRNA gene sequencing. He was diagnosed with cardiac actinomycosis, likely due to mediastinal infiltration from a lung infection, with haematogenous spread and treated with Penicillin G with adjunctive high-dose steroid therapy with resolution of symptoms and marked improvement in TTE features of constriction after 6 weeks. Discussion: Actinomycosis is an extremely rare cause of pericardial infiltration and constriction yet highly sensitive to penicillin, highlighting the importance of accurate diagnosis. Corticosteroids are a useful adjunct to prevent chronic constrictive pericarditis and to avoid the high morbidity and mortality associated with pericardiectomy.
