Major Clues and Pitfalls in the Differential Diagnosis of Parathyroid and Thyroid Lesions Using Fine Needle Aspiration Cytology.

Hwa Jeong Ha,Jung-Soon Kim,Myung-Soon Shin,Eun Ju Kim,Jae Soo Koh,Sunhoo Park,Seung-Sook Lee,Insup Noh

doi:10.3390/medicina56110558

Abstract

Background: It is difficult to distinguish parathyroid lesions (PLs) from thyroid lesions using fine needle aspiration cytology (FNAC) because of their proximity and their similar cytomorphological features. Methods: FNAC smears of 46 patients with pathologically proven PLs that were histologically diagnosed as parathyroid adenoma (PA, n = 35), parathyroid hyperplasia (PH, n = 3), atypical parathyroid adenoma (APA, n = 1), and parathyroid carcinoma (PC, n = 7) were retrospectively reviewed and analyzed. Results: Our initial cytological diagnoses indicated correct diagnoses in 31 of 46 PL patients (67%). The 15 erroneous diagnoses were 5 patients with non-specific benign disease (11%), 4 with nodular hyperplasia of the thyroid (9%), 5 with atypical cells (11%), and 1 with a metastatic papillary thyroid carcinoma (2%). Follicular pattern, papillary structures, colloid-like material, and macrophages, which often suggest thyroid lesions, were also present in some PLs. We found that branching capillaries along the papillary structures, stippled nuclear chromatin, and frequent occurrence of naked nuclei were useful for determining a parathyroid origin. Conclusions: It is important to be aware that PLs are frequently mistaken for thyroid lesions based on FNAC. The specific and unique characteristics of PLs identified here may be helpful in diagnosis.

Highlights

Parathyroid adenomas are very common, probably a daily finding in most endocrine clinics [1,2]
33 out of 46 patients were suggested as parathyroid lesion, and the remaining 13 cases represented various sonographic diagnoses including papillary thyroid carcinoma, tuberculous lymphadenopathy, and so on (Table 1)
IHC; and because of the low cellularity; parathyroid lesions (PLs) were diagnosed in five patients without performing IHC; and IHC IHC

Summary

Introduction

Parathyroid adenomas (not parathyroid carcinomas) are very common, probably a daily finding in most endocrine clinics [1,2]. Methods: FNAC smears of 46 patients with pathologically proven PLs that were histologically diagnosed as parathyroid adenoma (PA, n = 35), parathyroid hyperplasia (PH, n = 3), atypical parathyroid adenoma (APA, n = 1), and parathyroid carcinoma (PC, n = 7) were retrospectively reviewed and analyzed. Follicular pattern, papillary structures, colloid-like material, and macrophages, which often suggest thyroid lesions, were present in some PLs. We found that branching capillaries along the papillary structures, stippled nuclear chromatin, and frequent occurrence of naked nuclei were useful for determining a parathyroid origin. Eleven lesions (24%) had inspissated extracellular colloid-like material in the cell nests (Figure 6a), and eight lesions (17%) had macrophages in the background (Figure 6c). They were similar to the findings in the NH of thyroid (Figure 6b,d).

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Discussion

Conclusion