Autoimmune polyglandular syndrome type 2 presenting with pericardial effusion: a diagnostic challenge

Background: Autoimmune Polyglandular Syndrome Type 2 (APS-2), or Schmidt syndrome, is a rare autoimmune disorder marked by the coexistence of Addison’s disease with autoimmune thyroid disease and/or type 1 diabetes mellitus. Its nonspecific symptoms often lead to delayed diagnosis. While pericardial effusion is an uncommon manifestation of APS-2, it can pose diagnostic challenges. Case Presentation: A 44-year-old female presented with progressive pedal edema, facial puffiness, and dyspnea for three months. Clinical examination revealed non-pitting pedal edema, hyperpigmentation, dry skin, and muffled heart sounds. Investigations showed pericardial effusion confirmed by echocardiography, with transudative fluid secondary to hypothyroidism, as evidenced by elevated TSH and positive anti-TPO antibodies. The patient was treated with thyroxine and diuretics. During hospitalization, she developed worsening dyspnea, hypotension, and hypoglycemia, raising suspicion of adrenal insufficiency. Morning cortisol and ACTH levels confirmed primary adrenal insufficiency, leading to the diagnosis of APS-2. Treatment with intravenous hydrocortisone stabilized her condition, with significant clinical improvement. Discussion: This case highlights the diagnostic complexity of APS-2, particularly with atypical initial presentations like pericardial effusion. The pericardial effusion was attributed to hypothyroidism, a rare but recognized cause. Delayed recognition of adrenal insufficiency often complicates APS-2 diagnosis, necessitating high clinical suspicion for timely intervention. Conclusion: This case emphasizes the importance of recognizing multisystemic symptoms suggestive of APS-2. Prompt diagnosis and treatment with hormone replacement therapy can prevent life-threatening complications, underscoring the need for a comprehensive endocrine evaluation in patients with atypical presentations.