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Systemic lupus erythematosus involves the kidneys in a large percentage of cases, and less frequently, there is the presence of myocardial damage with a prevalence of 8-25%.
Case report that was presented at Hospital Universitario, Monterrey, Nuevo León, México.
This is a 42-year-old male with a past medical history of pleural tuberculosis diagnosed three years ago, presenting with refractory exudative left pleural effusion, dyspnea, and pleuritic pain. He also has a three-year history of type 2 diabetes mellitus. His current symptoms include recurrent progressive dyspnea, bilateral pleural effusion with characteristics of transudate, orthopnea, and paroxysmal nocturnal dyspnea. Physical examination reveals bilateral pleural effusion, intolerance to lying down, no retinopathy on fundoscopy, and no signs of overload or peripheral edema.
Laboratory findings include hemoglobin (Hb) of 11.7 g/dL, normocytic normochromic anemia, estimated glomerular filtration rate (eGFR) by CKD-EPI of 28 mL/min/1.73m2, proteinuria of 8.9 grams per 24 hours with an inverted albumin/globulin ratio. Echocardiogram shows an ejection fraction (EF) of 23%. Serological tests for light chains and serum protein electrophoresis rule out monoclonal gammopathy. ANA serology is positive at 1:640, with negative antibodies for anti-dsDNA, anti-SSA-Ro, SS-B/La, anti-Smith, anticardiolipins, anti-beta-2 glycoproteins, and lupus anticoagulant. C3 and C4 levels are normal.
Renal biopsy shows negative staining with Congo red, indicating glomerulonephritis due to immune complexes with a membranoproliferative and nodular pattern. Immunofluorescence reveals a diffuse, global, and granular "full house" pattern. Due to discordant findings, positive anti-U1-RNP antibodies (1:>200) are detected, and electron microscopy reveals fibrillary deposits measuring 10-20 nm.
Anti-nucleosome and anti-dsDNA antibodies show high sensitivity and specificity for lupus nephritis. The presence of antibodies against nuclear ribonucleoprotein (anti-RNP) and the occurrence of myocarditis are related to autoimmune activity against striated muscle in general. Myocarditis occurs in 5% to 10% of patients with SLE, and atypical serology, unusual clinical presentation, and nodular biopsy make the diagnosis challenging, requiring electron microscopy for the diagnosis of fibrillary glomerulopathy associated with Systemic lupus erythematosus.