Seroconversion of SSA and the Development of Inflammatory Myositis in a Patient With Chronic Joint Pain: A Potential Overlap Connective Tissue Disease.

We present the case of a 48-year-old female with a complex medical history, including chronic joint pain on methadone and chronic obstructive pulmonary disease (COPD), who developed right forearm myositis following a series of orthopedic procedures and infections. Initially thought to be infectious in origin, subsequent investigations revealed chronic inflammation without infection. The patient's serologic profile evolved over time, with new-onset SSA antibody positivity, positive antinuclear antibody (ANA) and rheumatoid factor (RF), and concern for overlapping connective tissue disease. This case highlights the diagnostic complexity and evolving nature of autoimmune conditions, particularly in patients with non-specific musculoskeletal symptoms and comorbidities.