Anti-Ro-Positive Lupus-Like Multisystem Inflammatory Syndrome After BNT162b2 COVID-19 Vaccination: A Case Report

Rare immune-mediated syndromes following COVID-19 vaccination have been described across a heterogeneous clinical spectrum.Anti-Ro/SSA-positive multisystem presentations with features of undifferentiated connective tissue disease (UCTD) or subacute cutaneous lupus erythematosus (SCLE) remain under-reported.A 66-year-old Caucasian man with no prior autoimmune history developed a progressive multisystem inflammatory illness approximately 14 days after receiving his second dose of the BNT162b2 (Pfizer-BioNTech) COVID-19 vaccine.Clinical features included an erythematous malar and dorsal rash, pharyngitis, geographic tongue, constitutional upset with profound fatigue, night sweats, and unintentional weight loss of 12 kg.Investigations revealed normocytic anaemia, elevated inflammatory markers, and bilateral pleural effusions.Positron emission tomography-computed tomography (PET-CT) demonstrated metabolically active mediastinal, supraclavicular, and pelvic lymphadenopathy with increased bone marrow and splenic uptake.Autoimmune serology showed a positive antinuclear antibody (ANA) test and strongly positive anti-Ro/SSA antibodies, with negative anti-double-stranded DNA (anti-dsDNA) antibodies, normal complement levels, and negative antineutrophil cytoplasmic antibodies (ANCA).Extensive investigation excluded malignancy, infection, sarcoidosis, and classical systemic lupus erythematosus (SLE).A lower limb deep vein thrombosis developed during hospitalisation.Systemic corticosteroids produced clear and sustained clinical and radiological improvement.The serological and clinical phenotype (anti-Ro-positive, anti-dsDNA-negative, complement-normal, without nephritis) is most consistent with UCTD or SCLE with systemic involvement rather than classical SLE.This case contributes to the emerging literature on post-vaccination autoimmunity, emphasises the importance of precise serological phenotyping, and highlights the need for structured long-term follow-up to determine whether such presentations represent transient immune dysregulation or the onset of persistent connective tissue disease.