Parathyroid Hormone (PTH) Assay of Parathyroid Cysts Examined by Fine-Needle Aspiration Biopsy

Abstract

The authors report three cases of parathyroid cysts examined by the fine-needle aspiration biopsy technic. A presumptive diagnosis of parathyroid cyst was made when characteristic water-clear fluid was aspirated. The diagnosis was then confirmed by parathyroid hormone (PTH) assay. The authors believe that the C-terminal/midmolecule determination should be the assay of choice, because the N-terminal-specific assay gave normal or slightly elevated results in all the cases studied. If only an N-terminal-specific PTH assay is obtained, potential for a false negative diagnosis exists. With a correct PTH assay, a specific diagnosis of parathyroid cyst can be rendered, which enables appropriate treatment of total fluid aspiration, which thereby eliminates the need for thyroid hormone treatment or surgery in most cases. A discussion of PTH assays is presented along with speculations concerning the secretion of PTH by the parathyroid gland. The previous literature detailing cytologic findings and the PTH assays of parathyroid cysts diagnosed by the fine-needle aspiration biopsy are reviewed.

A single-institution 25-year review of true parathyroid cysts

“…This series represents the largest single-institution experience of true non-functional PCs published to date. They are reported to occur in 0.5% of parathyroid diseases [4] and represent 1% of all cystic lesions of the neck [5]. Mediastinal localization has been reported in up to 30% of cases [6].…”

Oncocytic parathyroid adenoma: Problem in cytological diagnosis

“…2,6 Special techniques, such as immunoperoxidase staining for the PTH and thyroglobulin, chromogranin, and assays of the PTH level of the aspirated fluid might be helpful. 2,8,9 We report two cases of parathyroid adenomas that on FNA specimens due to the fact that the presence of monotonous proliferation of oncocytic cells were misinterpreted as Hurthle cell thyroid neoplasm. In both cases, parathyroid adenomas were oncocytic, intrathyroidally located, and associated with normal or mildly increased calcium levels.…”

Diagnostic and therapeutic review of cystic parathyroid lesions

“…Most authors suggest the measurement of the intact PTH molecule in order to avoid false negative results when using N-terminal PTH assays. [40][41][42] Parathyroid NA cytology findings often overlap with those observed from thyroid epithelium. In these cases, special cytologic features such as the absence of colloid and specific patterns of vascularization and granularity are highly indicative of a parathyroid origin tissue.…”