Needle aspirate PTH in diagnosis of primary hyperparathyroidism due to intrathyroidal parathyroid cyst

Abstract

SummaryParathyroid cysts are rare (0.8–3.41% of all parathyroid lesions) and usually arise secondary to cystic degeneration of parathyroid adenomas. Intrathyroidal parathyroid cysts are extremely rare with only three cases reported till date. We present a 24-year-old female with clinical and biochemical features of primary hyperparathyroidism (PHPT; Ca2 +: 12.1 mg/dl; intact parathyroid hormone (iPTH): 1283 pg/ml) and poor radiotracer uptake with minimal residual uptake in the left thyroid lobe at 2 and 4 h on Tc99m sestamibi imaging. Neck ultrasonography (USG) revealed 0.6×1 cm parathyroid posterior left lobe of thyroid along with 22×18 mm simple thyroid cyst. USG-guided fine-needle aspiration (FNA) and needle tip iPTH estimation (FNA-iPTH) from parathyroid lesion was inconclusive (114 pg/ml), necessitating FNA of thyroid cyst, which revealed high iPTH (3480 pg/ml) from the aspirate. The patient underwent a left hemithyroidectomy. A >50% drop in serum iPTH 20 min after left hemithyroidectomy (29.4 pg/ml) along with histopathology suggestive of intrathyroidal cystic parathyroid adenoma (cystic lesion lined by chief cell variant parathyroid cells without any nuclear atypia, capsular or vascular invasion surrounded by normal thyroid follicles) confirmed that the parathyroid cyst was responsible for PHPT. This report highlights the importance of FNA-iPTH in localizing and differentiating a functional parathyroid lesion from nonfunctional tissue in PHPT.Learning points Fine-needle aspiration from suspected parathyroid lesion and needle tip iPTH (FNA-iPTH) estimation from the saline washing has an important role in localizing primary hyperparathyroidism (PHPT).FNA-iPTH estimation may help in differentiating functional from nonfunctional parathyroid lesion responsible for PHPT.iPTH estimation from aspirate of an intrathyroid cyst is helpful in differentiating intrathyroidal parathyroid cyst from thyroid cyst.

Fine-Needle Aspiration Biopsy with PTH Measurement for Confirmation of Parathyroid Adenoma. Case Report

“…Ectopic parathyroid adenoma is a well-recognized entity and can occur anywhere from the upper part of the neck to the mediastinum due to abnormal migration of parathyroid cells during embryogenesis. Intrathyroidal parathyroid mixed lesions/cysts are extremely rare (23). At our institution we routinely perform outpatient USGguided FNA biopsy of thyroid nodules and we decided to perform a FNA on the suspected tumor followed by measurement of PTH in the aspirated liquid.…”

Small nonfunctional parathyroid cysts: single institution experience

“…Thyroid disorders and other diseases may be visualized as PCs, e.g., cysts and hypoechoic nodes at the posterior thyroid edge, in particular multinodular goiter, branchial cysts, thyroglossal cysts, other neck tumors, and metastases from other tumors, which can also develop cystic-degenerative lesions. Pathologically altered PGs, and occasionally PCs, may be located within the thyroid and therefore cannot be differentiated from thyroid nodes [1,[17][18][19][20][21][22][23][24].…”

“…Occasionally, it may be necessary to perform FNA of more than one suspect mass, frequently from several sites. Parathyroid cyst FNA generally yields clear, colorless, water-like or golden-brown fluid [1,2,7,11,13,[25][26][27]. Aspirate sediment should be examined on a microscope, along with determination of aspirate PTH.…”

Fine-Needle Aspiration Cytology of Parathyroid Lesions

“…1 Diffuse glandular hyperplasia accounts for 6% of cases, and cancers are a rare cause responsible for only 1% to 2% of PHPT. While hyperplasia is a diffuse process affecting all glands, adenoma and carcinoma typically involve a single gland.…”