Paraneoplastic Systemic Lupus Erythematosus in Papillary Thyroid Carcinoma: A Rare Case of Autoimmune-malignancy Interplay

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by multisystem involvement.Its association with malignancies, particularly thyroid carcinoma, is rare but clinically significant.We report a unique case of paraneoplastic SLE in a 48-year-old female with a history of papillary thyroid carcinoma.The patient presented with fever, weight loss, joint pain, and skin manifestations, including a malar rash and oral ulcers.Laboratory findings revealed pancytopenia, proteinuria, positive antinuclear antibodies (ANA), and anti-TPO antibodies, leading to a diagnosis of SLE.Imaging studies demonstrated hypermetabolic lymphadenopathy and residual thyroid activity.Immunosuppressive therapy with methylprednisolone and hydroxychloroquine was initiated, and a total thyroidectomy was performed to address the underlying malignancy.The patient showed significant clinical improvement, with resolution of pancytopenia, fever, and skin lesions.This case highlights the complex interplay between autoimmunity and malignancy, emphasizing the importance of early recognition, a multidisciplinary approach, and tailored therapeutic strategies.Further research is needed to elucidate the mechanisms linking SLE and thyroid cancer and to optimize management protocols for such rare cases.