Noninvasive encapsulated follicular variant of papillary thyroid carcinoma (PTC) was reclassified as noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP). To date, no studies on NIFTP have been reported in Japan. This study aimed to evaluate the clinical, cytological, and pathological findings of 54 cases of NIFTP from a single center in Japan, and compare them with those in the western countries. There were no significant differences in age, sex, or tumor size between patients with NIFTP and those with invasive encapsulated follicular variant -PTC. Ultrasound investigation showed a high suspicion lesion in 6.5% of NIFTP and 44.1% of invasive encapsulated follicular variant -PTC (p<0.001). On fine needle aspiration cytology, 75.7% of NIFTP cases were reported as suspicious for malignancy or malignant. Nuclear grooves and irregular-shaped nuclei were observed in 94.6% of cases of NIFTP. Pathologically, 27.8% cases of NIFTP and 13.0% cases of invasive encapsulated follicular variant -PTC had been originally diagnosed as macrofollicular variants of PTC. There were no NIFTP cases with nodal metastasis. We concluded that NIFTP should be renounced noninvasive encapsulated follicular variant -PTC, and should be considered as a malignant tumor with exceeding indolent behavior, and lobectomy alone should be satisfactory for the diagnosis and treatment.

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Background We aimed to determine the indication of fine‐needle aspiration (FNA) for parathyroid adenoma (PA)‐suspected nodules and the cytological features of PA, and to discuss the ancillary techniques for diagnostic confirmation. Method Clinical, cytological, and histological examinations of 15 PA patients (4.0% of all PA resected patients) were conducted through FNA on 16 nodules. We also examined the cytological preparations of 10 follicular neoplasms (FNs) and 10 poorly differentiated thyroid carcinomas (PDTCs). Results FNA was performed to detect PA in nine (56.3%) nodules. The remaining seven (43.8%) nodules underwent FNA for lesions considered as thyroid nodules or lymph nodes. The levels of parathyroid hormone (PTH) in the aspiration needle washout fluid were observably high, except for that from one nodule with unsatisfactory FNA. Cytologically, the incidences of wedge pattern (86.7%) and salt and pepper chromatin (86.7%) in PAs were significantly higher than in FNs and PDTCs. In contrast, the appearance of colloid globules and nuclear grooves was less frequent than that of FNs and PDTCs. GATA‐3 expression was intense in all PAs that immunocytochemistry were performed. Histologically, capsular invasion and/or laceration, tumor seeding, granulation tissue, and fibrosis were observed. Conclusions When PA localization is unusual or inconclusive despite extensive imaging, FNA may be performed. We asserted that wedge pattern, salt and pepper chromatin, and the absence of colloid globules and nuclear grooves are diagnostic cytological indicators of PA rather than of FN or PDTC. We recommend PTH measurements using needle washout fluid for PA‐suspected nodules, and immunocytochemistry with the GATA‐3 antibody for cytologically PA‐suspected nodules.

Introduction: Thyroid fine-needle aspiration cytology is the most reliable preoperative diagnostic tool, but cases of failed or unsatisfactory diagnostic can occur. Therefore, we aim to improve aspiration and smearing techniques. We handle approximately 8000 thyroid fine-needle aspiration cytology cases annually. Here, we present the aspiration and smearing techniques resulting from our accumulated experience. Materials and Methods: Patients undergo aspiration cytology while seated on a barber chair, and are asked to gaze upwards to extend their anterior neck. 1 Instead of relying on suction force, the samples are mainly obtained by cutting the tissue with needle movements. A strong negative pressure and a long aspiration time frequently produce bloody samples. Hence, we recommend negative pressure <0.3 mL and aspiration time up to 3 seconds. The obtained samples are placed on a glass slide and smeared using a second slide glass through a press and release method. When the samples are bloody, we tilt the glass slide, remove excess material, and wipe up the bloody components flowing from the slide. Liquid-based cytology is especially recommended for bloody or fluid samples. Biochemical measurement of thyroglobulin and calcitonin using fine-needle washout fluids is useful for diagnosing metastatic differentiated thyroid carcinoma and medullary thyroid carcinoma. 2,3 When lymphoma is suspected, flow cytometry using aspirated samples is recommended. 4 Results: By applying the mentioned techniques and recommendations, we observed an increased accuracy in diagnosis and improved quality of our examinations. Conclusions: Fine-needle aspiration requires aspirating from the areas suitable for the diagnosis, obtaining adequate materials, and performing optimal smearing and fixation to retrieve highly accurate diagnoses. We hope our methods are helpful in improving your fine-needle aspiration cytology techniques, and result in more accurate cytological diagnoses. Thank you for taking interest in our methods.

We introduce the Japanese reporting system for thyroid aspiration cytology 2019 (JRSTAC2019) proposed by the Japan Association of Endocrine Surgery and the Japanese Society of Thyroid Pathology.Pathological classification and recommended clinical management for thyroid nodules in Japan are different from those described in the World Health Organization classification or the Bethesda System for Reporting Thyroid Cytopathology (TBSRTC). Therefore, it was necessary to develop a reporting system adapted for Japan. JRSTAC2019 is a modified version of TBSRTC. Currently, JRSTAC2019 is widely used in Japan, although the details of the system have not been introduced in English. JRSTAC2019 comprises seven categories: (I) unsatisfactory, (II) cyst fluid, (III) benign, (IV) undetermined significance, (V) follicular neoplasm (FN), (VI) suspicious for malignancy (SFM), and (VII) malignant. "Cyst fluid" nodules are classified as an independent category, and "recommended management" is in the same category as "benign" nodules. Surgical resection for FN nodules is decided upon by considering several parameters, and the decision is made without performing gene analysis. Non-invasive follicular thyroid neoplasm with papillarylike nuclear features tends to be more often diagnosed as papillary carcinoma. The risk of malignancy of SFM in Japan is higher than that in Western countries, and resection rates of SFM and malignant tumors are lower owing to active surveillance for low-risk papillary microcarcinoma. We recommend that each country should develop its reporting system, suitable for its medical and social needs. However, it should be easily compatible with TBSRTC for the ease of academic data sharing.