Value of thyroglobulin measurement of cystic neck mass fluid aspirate

Cystic neck masses have a wide differential diagnosis. Fine-needle aspiration cytology with or without thyroglobulin washout may be non-diagnostic or false-negative, while a primary thyroid tumour may be sonographically occult. We aim to demonstrate the value of biochemical thyroglobulin measurement in directly aspirated cyst fluid in diagnosis or exclusion of papillary thyroid cancer cystic nodal metastases.

Prospective case series (n = 10) of patients presenting with a lateral cystic neck mass with or without thyroid abnormality, where thyroglobulin measurement of aspirated cyst fluid was part of the diagnostic workup.

N1b papillary thyroid cancer diagnosis was predicted by elevated thyroglobulin in cyst fluid aspirate in seven cases, all greater than 200 µg/L, confirmed at surgical resection. Papillary thyroid cancer nodal metastasis was refuted by low thyroglobulin result in three benign cystic lesions, all less than 6 µg/L.

Biochemical thyroglobulin analysis of fluid aspirate is a valuable adjunct for evaluation of cystic neck masses and pre-operative diagnosis of papillary thyroid cancer cystic nodal metastases.