Nodal Papillary Thyroid Carcinoma Without an Identified Thyroid Primary

Papillary thyroid carcinoma in a cervical lymph node without an identified primary tumor in the thyroid gland poses a diagnostic challenge. A 27-year-old man underwent excision of a right laterocervical lymph node, which showed papillary carcinoma of thyroid origin. Subsequent total thyroidectomy showed normal thyroid parenchyma, and lymph node dissection identified one involved upper mediastinal node among 49 examined nodes. Six weeks after surgery, the patient received 3.7 GBq of iodine-131. Post-therapy whole-body scintigraphy and SPECT/CT showed uptake in a thyroid-bed remnant without other reported pathological foci. A favorable course was reported at six months, with continued surveillance. An intranodal ectopic thyroid origin was considered, but an occult thyroid primary remains a differential diagnosis. The findings support nodal papillary thyroid carcinoma without an identified thyroid primary; they do not establish the site of origin.