Abstract
BackgroundThe number of extensive studies focusing on cyst fluid only (CFO) thyroid nodules is limited, and the risk of malignancy (ROM) in CFO nodules has not been well‐established. Thus, the purpose of this study was to investigate CFO nodules using cytology and ultrasound. In addition, we sought to define the ROM and determine the recommended clinical management of CFO nodules.MethodsWe retrospectively reviewed cytological preparations of 678 nodules that were originally identified as CFO nodules, including conventional specimens in 209 nodules, liquid based cytology (LBC) specimens in 221 nodules, and both conventional and LBC specimens in 248 nodules. Ultrasound reports with representative photographs were also reviewed.ResultsOf the 678 CFO nodules, 214 (31.6%) were reclassified into other categories, including non‐diagnostic/unsatisfactory (ND/UNS) except for CFO (n = 15), benign (n = 198), and malignant (n = 1). Conventional preparations (33.5%) were more frequently reclassified than LBC preparations (13.6%; P < .0001). Re‐aspiration for diagnosis was performed for only one calcified nodule. The rates of surgical resection and malignancy were 3.0% and 0.2%, respectively. Based on American Thyroid Association guidelines and the Kuma Hospital ultrasound classification, worrisome sonographic features were identified in 5.8% and 0% of CFO nodules, respectively.ConclusionWe propose that CFO nodules should be classified as separate from ND/UNS nodules; they should be categorized as a subtype of benign nodules. However, it is essential that fine‐needle aspiration cytology be performed under ultrasound‐guided real‐time visualization of needle placement in the target nodule in all cases.
Highlights
According to The 2017 Bethesda System for Reporting Thyroid Cytopathology (TBSRTC),[1] the diagnostic categories for thyroid nodules are classified as “non-diagnostic or unsatisfactory (ND/UNS),” “benign,” “atypia of undetermined significance (AUS),” “follicular neoplasm (FN),” “suspicious for malignancy (SFM),” and “malignant,” and the risk of malignancy (ROM) and recommended clinical management are specific to each category
We reviewed a database of the cytology reports of 7295 patients that underwent thyroid fine-needle aspiration cytology (FNAC) at Kuma Hospital from January to December 2017
According to the American Thyroid Association (ATA) guidelines and TBSRTC,[1,4] preparations exhibiting degenerated cyst fluid contents, with or without histiocytes, and fewer than six groups of 10 benign follicular cells are classified as ND/UNS, because the possibility of cystic papillary thyroid carcinoma cannot be excluded
Summary
According to The 2017 Bethesda System for Reporting Thyroid Cytopathology (TBSRTC),[1] the diagnostic categories for thyroid nodules are classified as “non-diagnostic or unsatisfactory (ND/UNS),” “benign,” “atypia of undetermined significance (AUS),” “follicular neoplasm (FN),” “suspicious for malignancy (SFM),” and “malignant,” and the risk of malignancy (ROM) and recommended clinical management are specific to each category. When the sonographic features suggestive of malignancy, the endocrinologist is not convinced that the sample is representative, and it might be clinically ND/UNS.[5] CFO nodules have two different clinical managements that can be determined based on ultrasound findings. The purpose of the current study was to review cytological and ultrasound findings of CFO nodules, define the ROM, and determine the recommended clinical management of CFO nodules. The number of extensive studies focusing on cyst fluid only (CFO) thyroid nodules is limited, and the risk of malignancy (ROM) in CFO nodules has not been well-established. Results: Of the 678 CFO nodules, 214 (31.6%) were reclassified into other categories, including non-diagnostic/unsatisfactory (ND/UNS) except for CFO (n = 15), benign (n = 198), and malignant (n = 1). It is essential that fine-needle aspiration cytology be performed under ultrasound-guided real-time visualization of needle placement in the target nodule in all cases
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