Systemic sclerosis presenting as recurrent pericardial effusion despite repeatedly negative multiplex antinuclear antibody results.

A woman in her 70s was admitted three times over 22 months with recurrent pericardial effusions. A multiplex antinuclear antibody (ANA) assay by chemiluminescent enzyme immunoassay, reported only as a combined index, was repeatedly negative. Reassessment with careful history revealed long-standing Raynaud's phenomenon and episodic abdominal bloating, prompting further evaluation for systemic sclerosis (SSc). Indirect immunofluorescence (IIF) on HEp-2 (human epithelial type 2) cells showed ANA positivity (fine speckled 1:640 and nucleolar 1:320) and ELISA detected anti-RNA polymerase III antibodies, confirming SSc. Because of pre-existing renal impairment and anti-RNA polymerase III positivity, glucocorticoids were avoided; colchicine 0.5 mg/day was started to prevent recurrence. No further pericardial effusion occurred during follow-up. This case illustrates that relying solely on a combined-index multiplex ANA screen can delay diagnosis and that HEp-2 IIF and disease-specific antibody testing are essential when clinical suspicion persists.