Occult papillary carcinoma of the thyroid presenting as a cervical cyst

Background. A cystic neck mass representing metastatic papillary thyroid cancer to a cervical lymph node may be the presenting symptom In patients with an occult papillary cancer of the thyroid. This cystic change can cause diagnostic problems and not infrequently delay identification of the primary thyroid tumor. This study investigates the frequency, treatment, and pathologic features of this entity. Methods. All clinical charts and microscopic slides of 136 consecutive patients who underwent thyroid operation for papillary carcinoma (PC) from 1990 to 1995 were reviewed. Hematoxylin-and-eosin and immunohistochemical stains (IMHS) for thyroglobulin also were reviewed. Results. Eight patients (5.8%) presented with a cystic neck mass and no palpable thyroid lesion. In all 8 patients, the diagnosis was made by an excision of the cystic neck mass. In 3 patients, the cyst demonstrated classical features of PC, such as papillae and psammoma bodies. In the remaining 5 (62 %), only focal papillae or nuclear features of papillary carcinoma were present. A careful review of the histology and IMHS were necessary to arrive at the correct diagnosis in these 5 patients. Conclusions. Occult papillary cancer of the thyroid presenting as a cystic neck mass is not uncommon and must be considered in the differential diagnosis. Excision and careful review of the histology and IMHS is necessary to prevent delay of the proper diagnosis. Although the thyroid tumor was less than I cm and sometimes only microscopic, the extensive nodal metastasis has led us to favor near total or total thyroidectomy and modified neck dissection in this entity.