Castleman disease mimicking nodal recurrence of thyroid cancer.

A 54-year-old woman who had undergone total thyroidectomy and radioactive iodine treatment for papillary thyroid cancer presented with elevated stimulated thyroglobulin levels and negative I-131 scan. Ultrasonography revealed suspicious lateral neck lymph nodes, which were FDG-avid. Neck dissection led to a diagnosis of Castleman disease.