Evolving autoimmune thyroid disease in the postpartum period with incidental identification of papillary thyroid microcarcinoma: A case report.

Postpartum immune rebound may precipitate autoimmune thyroid disease. The sequential development of postpartum thyroiditis, Graves' disease, Hashimoto thyroiditis, and papillary thyroid carcinoma in a single patient has not previously been described. A 30-year-old woman (G3P1204) presented five months after a preterm dichorionic-diamniotic twin delivery (at 32 weeks 2 days) with thyrotoxicosis and weight loss. Laboratory evaluation showed suppressed thyroid stimulating hormone, positive thyrotropin receptor antibodies, and elevated thyroid peroxidase antibodies. Radioiodine uptake was low, consistent with postpartum thyroiditis. She subsequently developed thyroid eye disease and persistent autoimmune seropositivity. Progressive thyroid nodules prompted total thyroidectomy, which incidentally revealed papillary thyroid carcinoma (<1 cm) on a background of chronic lymphocytic thyroiditis and treated Graves' disease. This case highlights the diagnostic and management challenges of overlapping postpartum autoimmune thyroid disorders and underscores the importance of surveillance when structural thyroid abnormalities coexist.