Endocrine Abstracts

A 21-year-old woman underwent total thyroidectomy and unilateral central neck dissection for papillary thyroid carcinoma. Four of the removed lymph nodes tested positive for metastasis. Additional radioactive iodine treatment was given and the post I-131 therapy total body scan showed increased uptake of iodine-131 in a thyroid remnant but none in any of the lymph nodes. Postoperatively thyroglobulin levels decreased but remained elevated. During follow-up, a nodular enlargement was palpable in the patient’s neck. Ultrasound revealed a suspicious lymph node with a diameter of > 5 cm, localized posteriorly to the sternocleidomastoid muscle. Fine needle aspiration (FNAC) and biopsy showed no evidence for metastatic disease. However, FDG-PET/CT showed mild metabolic hyperactivity. Given this context, after multidisciplinary consultation, a neck dissection was performed. The result showed Castleman disease. Although this entity is rare, Castleman disease has to be considered in the differential diagnosis of cervical nodular lesions. This case demonstrates Castleman disease as a possible condition to be confused with recurrence of thyroid carcinoma and the potential use of FDG-PET/CT in patients with measurable thyroglobulin levels but negative post I-131 therapy total body scan in the followup of thyroid carcinoma.