Lupus Mastitis with Cardiopulmonary Involvement in Overlap Syndrome

Systemic lupus erythematosus (SLE) is a complex autoimmune disorder with multisystem involvement, including rare variants like lupus panniculitis (LP). This variant is characterized by chronic inflammation of subcutaneous fat. Lupus mastitis (LM), an uncommon manifestation of LP, involves the breast's deep subcutaneous fatty tissue and presents usually as a diagnostic challenge. We describe a healthy young lady in her mid-twenties who presented with bilateral breast pain and swelling. Further evaluation revealed lupus mastitis as the initial manifestation of an overlap syndrome involving systemic lupus erythematosus and polymyositis, with associated cardiopulmonary involvement. She experienced several symptoms including proximal muscle weakness, and respiratory symptoms. Following immunosuppressive therapy with corticosteroids, mycophenolate mofetil, hydroxychloroquine, and rituximab, she showed significant clinical improvement across all affected systems. This case highlights the importance of thorough evaluation in patients presenting with breast swelling, emphasizing the need to avoid unnecessary surgical interventions, and underscores the effective management strategies for complex cases of LM associated with overlap syndrome.