Authors
Mohammed N Taha, Moath Al-Shudifat
Published in
Cureus. Volume 18. Issue 6. Pages e110681. Epub Jun 11, 2026.
Abstract
Pericardial effusion, defined as the abnormal accumulation of fluid within the pericardial sac, has a broad differential diagnosis, and identifying the underlying etiology can be particularly challenging when multiple potential causes coexist. Mixed connective tissue disease (MCTD) is a rare systemic autoimmune disorder. MCTD is characterized by overlapping features of systemic lupus erythematosus (SLE), systemic sclerosis (SSc), and polymyositis in association with anti-U1 ribonucleoprotein antibodies (anti-U1-RNP). Although pericarditis is the most common cardiac manifestation of MCTD, large pericardial effusion as the initial presenting feature has been described in only a small number of case reports. We describe the case of a 62-year-old malnourished female (BMI 17.7 kg/m2) with a history of hypertension, hypothyroidism, and chronic dysphagia who presented with persistent nausea and vomiting. Laboratory evaluation revealed leukopenia, anemia, hypoalbuminemia (2.8 g/dL), subclinical hypothyroidism, and normal inflammatory markers. CT obtained for gastrointestinal symptoms incidentally revealed a large pericardial effusion. Transthoracic echocardiography confirmed a large circumferential effusion with an end-diastolic diameter of 4.87 cm and early tamponade physiology, including right atrial systolic collapse and significant respiratory variation in tricuspid inflow. Ultrasound-guided pericardiocentesis yielded approximately 1000 mL of clear yellow fluid; cultures and cytology were negative. The sausage-shaped swollen fingers seen clinically prompted serologic tests, which were positive for antinuclear antibodies (ANA), anti-U1-RNP, and anti-Sjögren's-syndrome-related antigen A (anti-SS-A) antibodies. Anti-double-stranded DNA (anti-dsDNA), anti-Smith, anti-Scl-70, and anti-centromere antibodies were negative. Esophagogastroduodenoscopy showed a lower esophageal stricture consistent with chronic reflux. The patient's findings were consistent with the Kasukawa classification criteria for MCTD, with the patient demonstrating anti-U1-RNP antibodies, swollen digits (a common symptom), pericarditis/serositis (an SLE-like feature), and esophageal involvement (an SSc-like feature). The patient improved after pericardiocentesis and nutritional optimization and was discharged with multidisciplinary follow-up. This case illustrates the diagnostic challenge of determining the etiology of a large pericardial effusion in a patient with multiple possible confounding factors, including malnutrition, subclinical hypothyroidism, and unrecognized autoimmune disease. Normal CRP and absence of fever were suggestive of a noninflammatory process, which may be seen in autoimmune pericardial disease, though a normal CRP is not specific for autoimmune pericarditis. While prior case reports have described large pericardial effusion as an initial manifestation of MCTD, the unique contribution of this case lies in the specific diagnostic challenge of disentangling MCTD from concurrent malnutrition and subclinical hypothyroidism in an elderly patient, a clinical scenario that underscores the importance of maintaining a high index of suspicion for autoimmune disease in patients with idiopathic pericardial effusions, even when nutritional or metabolic causes seem more likely.
PMID:
42437225
Bibliographic data and abstract were imported from PubMed on 12 Jul 2026.
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