Utility of fine-needle aspiration cytology in the identification of parathyroid lesions

Abstract

Objectives:Fine-needle aspiration cytology (FNAC) is a first-line investigation in the evaluation of neck nodules. In an attempt to search for reliable cytomorphological criteria for parathyroid lesions, we systematically evaluated cytomorphology of FNAC of parathyroid lesions.Study Design:FNAC of 15 parathyroid and 15 hyperplastic thyroid nodules with histological confirmation were reviewed for following features: Cellularity, follicles, bare nuclei, cohesiveness, vascular profiles, cytoplasmic granularity, intracytoplasmic vacuolation, mitosis, macrophages, and colloid.Results:Vascular proliferation, bare nuclei, intracytoplasmic fat vacuolation, absence of colloid, and high cellularity showed significant association with parathyroid lesions (P ≤ 0.05). Intracytoplasmic fat vacuolation was 53.3% sensitive and 100% specific for parathyroid. Follicular pattern and papillaroid clusters were also important; however, they achieved nearly significant statistical difference (P = 0.05 and P = 0.06, respectively). The combination of vascular proliferation and intracytoplasmic fat vacuolation were significantly associated with parathyroid (P = 0.006) whereas the absence of bare nuclei and the presence of background colloid were associated with thyroid cytomorphology (P = 0.03).Conclusion:No single cytological feature is helpful in differentiating parathyroid from thyroid lesion. Vascular proliferation, bare nuclei, intracytoplasmic fat vacuolation, high cellularity, and the absence of colloid were significantly associated with the parathyroid origin. The combination of at least two features — vascular proliferation and intracytoplasmic fat vacuoles — were highly suggestive of parathyroid origin.

Identification of parathyroid tissue in thyroid fine‐needle aspiration: A combined approach using cytology, immunohistochemical, and molecular methods

“…All samples were submitted as a thyroid nodule FNA, and represented 0.12% of the total thyroid FNAs examined over this period. Using previously published criteria, 47 samples (78%) displayed cytologic findings that were suggestive of PT cells, and were subsequently confirmed with IHC. Thirteen (13) samples (22%) had cytologic features that were not recognized as PT on initial ThinPrep evaluation and were classified using TBSRTC criteria as either AUS or SFN.…”

“…The cytologic features of parathyroid (PT) cells have been well described, both in conventional smears and in liquid‐based preparations . However, ectopic PT within the thyroid gland can be difficult to recognize, as both are neuroendocrine glands and show similar cytologic features . About 30% of these ectopic nodules are asymptomatic, and clinical and radiologic identification may also be difficult.…”

Distinguishing parathyroid and thyroid lesions on ultrasound‐guided fine‐needle aspiration: A correlation of clinical data, ancillary studies, and molecular analysis

“…Common major cytomorphologic features of parathyroid tissue that have been reported in the literature include a papillary-like pattern with fibrovascular cores or prominent vascular network/proliferation, stippled chromatin, follicular pattern, and bare nuclei (Table 5). 2,[4][5][6][7][8][9][18][19][20][21][22] The majority of these studies also concluded that a combination of cytomorphologic features supported by either ancillary studies or correlation with clinical, radiologic, and laboratory findings are important in establishing a correct diagnosis of parathyroid tissue. The main diagnostic features in the current study also included bare nuclei.…”

“…Dimashkieh and Krishnamurthy reported that nuclei measuring smaller than thyroid follicular cells, bare nuclei, stippled chromatin, and a prominent vascular network with adherent cells indicated parathyroid origin . Another study found vascular proliferation, bare nuclei, intracytoplasmic fat vacuolation, and high cellularity to be significantly associated with parathyroid origin …”

“…5 Another study found vascular proliferation, bare nuclei, intracytoplasmic fat vacuolation, and high cellularity to be significantly associated with parathyroid origin. 6 Histopathology in conjunction with parathyroid hormone (PTH) immunostaining remains the gold standard for accurate diagnosis. 3 Some studies have used immunohistochemical stains on specimens obtained from FNA to differentiate thyroid from parathyroid lesions.…”