Nami Takada

Diagnostic significance of PAX8 in thyroid squamous cell carcinoma

Most types of thyroid carcinomas express PAX8 transcription factor; however, whether thyroid squamous cell carcinoma (SCC) also expresses PAX8, currently remains unknown. We herein examined the immunoreactivity of PAX8 in SCC of thyroidal and extrathyroidal origin, and discussed the diagnostic significance of PAX8. We immunohistochemically examined specimens from 11 SCC, 22 papillary thyroid carcinoma (PTC), 8 anaplastic thyroid carcinoma (ATC), and 2 mucoepidermoid carcinoma (MEC) cases as well as 5 uterine cervical SCC, 5 esophageal SCC, and 5 pulmonary SCC cases. The rates of PAX8-positive SCC, PTC, ATC, and MEC were 90.9%, 90.9%, 75.0%, and 100%, respectively. Two PAX8-negative PTC cases were cribriform variants. No uterine cervical, esophageal, or pulmonary SCC specimen reacted with PAX8 antibody. Thyroid transcription factor-1 (TTF-1) was positive in 9.1% and 95.5% of SCC and PTC cases, respectively, but negative in all ATC and MEC cases. These results demonstrate that PAX8 staining is useful for distinguishing between primary thyroid SCC and invasion or metastasis from extrathyroidal SCC. We recommend using an immunohistochemical panel of antibodies to PAX8 and TTF-1 to confirm a diagnosis of primary thyroid carcinoma.

Reappraisal of “cyst fluid only” on thyroid fine-needle aspiration cytology

According to the Bethesda System for Reporting Thyroid Cytopathology (BSRTC), cyst fluid only (CFO) cases are classified in the non-diagnostic category. To date, no large study focusing on CFO has been conducted. To reassess the diagnostic significance of CFO, we compared CFO nodules with non-diagnostic nodules excluding CFO (ND-other). We reviewed the conventional thyroid smears of 715 CFO and 766 ND-other nodules. We compared the timing of and findings at re-aspiration, the histology of resected specimens, and the proportion of malignant nodules between the two groups. Re-aspiration was performed in 9.0% of CFO and 23.8% of ND-other cases. In 12.5% of CFO and 49.4% of ND-other cases, the interval between the first and second aspirations was <3 months. Despite this, there were no cases in which cytological interpretation was complicated by the first aspiration. Overall, 77 CFO nodules (10.8%) were surgically resected; 14 were malignant. In all cases in which re-aspiration cytology revealed malignancy, the initial ultrasound interpretation was a high or intermediate suspicion pattern. The proportion of malignancies subsequently diagnosed in nodules initially classified as CFO and ND-other was 2.0% and 5.6%, respectively (p<0.01). As CFO and ND-other thyroid nodules have different clinical management and malignancy rates, we would like to assert that CFO and ND-other nodules should be separated, and that the former should be considered diagnostic. In terms of clinical management, we recommend that only CFO cases with concerning features on ultrasound undergo re-aspiration.

Diagnostic value of GATA-3 in cytological identification of parathyroid tissues

Parathyroid and thyroid lesions appear morphologically similar in cytological smears, and their differentiation can be difficult. The purpose of this study was to determine the diagnostic value of T-cell-specific transcription factor GATA-3 as a marker of parathyroid differentiation in cytology specimens, and to examine the utility of liquid-based cytology (LBC). Cytology smears obtained from surgically removed parathyroid and thyroid specimens, including 15 normal parathyroid glands, 12 cases of parathyroid hyperplasia, 55 parathyroid adenomas, 2 follicular thyroid adenomas, and 3 papillary thyroid carcinomas, were examined by immunocytochemistry using antibodies against GATA-3, parathyroid hormone (PTH), chromogranin A, and thyroid transcription factor 1 (TTF-1). All normal and hyperplastic parathyroids and 98.2% of parathyroid adenomas were positive for GATA-3, while 33.3%, 66.7%, and 60.0% of them, respectively, were positive for PTH. The positive rates for chromogranin A among normal parathyroids (80.0%) and parathyroid adenomas (87.3%) were lower than those for GATA-3. At the same time, all thyroid-derived tumours were positive for TTF-1 and negative for GATA-3, PTH, and chromogranin A. LBC smears of 35 parathyroid lesions indicated that the positive rates for GATA-3, PTH, and chromogranin A were 97.1 %, 97.1%, and 100%, respectively, while in conventional smears, those for PTH (25.5%) and chromogranin A (78.7%) were significantly lower (p < 0.01). Our results suggest that GATA-3 is a more reliable biomarker than PTH or chromogranin A in differentiating parathyroid from thyroid lesions in cytology smears and that LBC is useful in detecting cytoplasmic antigens such as PTH and chromogranin A.

A Novel Germline Mutation of KEAP1 (R483H) Associated with a Non-Toxic Multinodular Goiter.

Background A germline mutation of KEAP1 gene was reported as a novel genetic abnormality associated with familial multinodular goiter. That report was limited, and the pathogenic features were not well established. Patient findings We report a 47-year-old Japanese woman who presented with hyperthyroidism and a large multinodular goiter. The family history was notable for a paternal history of goiter. Graves’ disease was diagnosed based on positive TRAb, but scintiscan imaging showed that the patient’s radioiodine uptake was restricted in the non-nodular areas, indicating largely cold nodules. A total thyroidectomy was performed. The resected thyroid tissue weighed 209 g, and subsequent pathological findings were benign. The patient had a germline heterozygous KEAP1 mutation, c. 1448 G > A, resulting in an amino acid substitution (p.R483H). A next-generation sequencing analysis covering all known genes associated with multinodular goiter showed no additional germline mutation. The nuclear accumulation of NRF2, a protein associated with KEAP1, was shown at much higher rates in the patient’s nodules compared with nodules obtained from four unrelated patients with multinodular goiters. Conclusion A novel germline mutation (R483H) of KEAP1 gene was associated with the development of a non-toxic multinodular goiter.

Differentiating between benign follicular nodules and follicular neoplasms in thyroid liquid-based cytology preparations

The cytological morphology observed in liquid‐based cytology (LBC) preparations is dissimilar to that of conventional preparations. The aim of this report is to clarify the cytological differences between benign follicular nodules (BFNs) and follicular neoplasms (FNs) in LBC preparations and identify novel diagnostic criteria for LBC preparations.

Can Ultrasound Alone Predict Papillary Thyroid Carcinoma with Desmoid-Type Fibromatosis? A Retrospective Analysis of 13 Cases, Focusing on the Stromal Area

Purpose Papillary thyroid carcinoma with desmoid-type fibromatosis (PTC-DTF) is extremely rare. So far, only 4 cases describing the ultrasound findings of this variant have been reported. Here, we describe the ultrasound findings of 13 cases of PTC-DTF, focusing especially on the DTF area. Materials and Methods We retrospectively analyzed the clinical reports, ultrasound reports, and ultrasound photographs obtained from medical records at Kuma Hospital. Results The patients included 8 women and 5 men with a mean age of 47.9 years. The widest dimension of the nodules ranged from 16 to 79 mm (mean: 37.5 mm). The original ultrasound reports classified the nodules as either intermediate suspicion or high suspicion. A diagnosis of PTC was suspected in 12 nodules, and anaplastic carcinoma was suspected in 1 nodule. PTC-DTF presented with an irregularly shaped nodule (100%), taller-than-wide sign (84.6%), heterogeneous echogenicity (100%), no microcalcification (76.9%), and no or mild flow signal on Doppler (75.0%). The DTF area was identified in the ultrasound photographs of 8 nodules. DTF areas were generally heterogeneous (62.5%) and more hypoechoic (71.4%) than PTC areas. Microcalcification was not observed in the DTF areas. All of the DTF areas revealed no or mild flow signal. On ultrasound elastography, the DTF areas were not stiff, and they were more elastic than the PTC areas. Conclusion It is difficult to predict PTC-DTF using ultrasound alone, and B-mode ultrasonography is more reliable than ultrasound elastography in the ultrasound diagnosis of malignant thyroid nodules.

Immunohistochemical and Molecular Analyses Focusing on Mesenchymal Cells in Papillary Thyroid Carcinoma with Desmoid-Type Fibromatosis

Objective: This study was designed to evaluate the prevalence of CTNNB1 (β-catenin) mutations in cases of papillary thyroid carcinoma with desmoid-type fibromatosis (PTC-DTF) expressing aberrant nuclear and cytoplasmic immunoreactivity for β-catenin. Methods: Eight cases of PTC-DTF were available for this study. Immunohistochemistry for β-catenin and BRAFV600E was performed. CTNNB1 and BRAFV600E mutations were also evaluated by direct sequencing. Results: For β-catenin, although we could demonstrate aberrant nuclear and cytoplasmic immunoreactivity in DTF components in all cases, suggesting activated Wnt signaling, direct sequencing revealed a missense mutation, c.121A>G (p.T41A), in exon 3 in only one case, and no mutations in exons 3, 4, and 5 in the other cases. In the BRAFV600E analyses, immunohistochemistry revealed positive staining in the carcinoma cells but not DTF components of all cases. These findings were subsequently validated by direct sequencing. Conclusion: This study suggests the significance of the BRAFV600E mutation and activation of Wnt signaling pathway in the carcinoma cells and DTF components, respectively. We believe that the CTNNB1 mutations are not the major factor behind β-catenin translocation indicating Wnt pathway activation. Further study is required to evaluate whether molecular abnormalities other than the CTNNB1 mutation cause activation of Wnt signaling in DTF components of PTC-DTF.

Derivation of thyroid lymphoepithelial cysts from follicular cells

The pathogenesis of thyroid lymphoepithelial cysts is controversial, and two hypotheses have been proposed, namely derivation from branchial-derived remnants or from squamous metaplasia of the follicular cells. The aim of this study was to clarify the pathogenesis of thyroid lymphoepithelial cysts. We performed pathological and immunohistochemical examination of 21 thyroid lymphoepithelial cysts, 13 non-neoplastic squamous metaplasia samples without thyroid carcinoma, 13 solid cell nests, and 14 lateral cervical cysts. On ultrasound, half of thyroid lymphoepithelial cysts were interpreted as calcified nodules regardless of no calcification. Thyroid lymphoepithelial cysts and squamous metaplasia tended to be located in the central and lower portions of the thyroid, while solid cell nests were located in the upper and central portions (p < 0.05). In 95.2% of patients with thyroid lymphoepithelial cysts and all patients with squamous metaplasia, lesions were histologically associated with chronic thyroiditis forming lymph follicles. Hashimotos disease was serologically confirmed in 18 patients with lymphoepithelial cysts (85.7%) and 10 patients with squamous metaplasia (76.9%). Immunohistochemically, lymphoepithelial cysts showed nuclear positivity for PAX8, thyroid transcription factor 1, and p63. One lateral cervical cyst (7.1%) showed positive staining for PAX8, while solid cell nests were PAX8-negative. In three (14.3%) cases of thyroid lymphoepithelial cysts, squamous cells located on the superficial layer were focally and weakly positive for CEA. We concluded that thyroid lymphoepithelial cysts originate from follicular cells and are unrelated to solid cell nests and lateral cervical cysts arising from branchial-derived remnants.

Identification of Cytological Features Distinguishing Mucosa-Associated Lymphoid Tissue Lymphoma from Reactive Lymphoid Proliferation Using Thyroid Liquid-Based Cytology

Objective: To identify cytological differences between mucosa-associated lymphoid tissue lymphoma (MALT-L) and nonneoplastic lymphocytes using thyroid liquid-based cytology (LBC). Study Design: We observed LBC and conventional specimens from 35 MALT-L cases, 3 diffuse large B-cell cell lymphoma (DLBCL) cases, and 44 prominent nonneoplastic lymphocytic infiltration cases. Results: In MALT-L cases, the incidence of lymphoglandular bodies in the LBC specimens was lower than that in the conventional specimens (p < 0.001). Moreover, the nuclear sizes in LBC specimens were larger than those in conventional specimens. In 62.9% of the MALT-L and all DLBCL specimens, large nuclei were present in > 10% of the lymphoid cells in LBC specimens. Two cases with prominent nonneoplastic lymphocytic infiltration also exhibited these findings. In LBC specimens, swollen naked nuclei with less punctate chromatin patterns and thin nuclear margins were observed in 92.1% of lymphoma and 20.5% of prominent nonneoplastic lymphocytic infiltration. Elongated nuclei were significantly more apparent in thyroid lymphoma than in prominent nonneoplastic lymphocytic infiltration (p < 0.001), with a significantly higher incidence in LBC specimens than in conventional specimens (p < 0.001). Conclusions: Lymphoglandular bodies are not reliable markers for lymphoma diagnosis using LBC specimens. Large, swollen naked, and elongated nuclei are useful in distinguishing thyroid lymphoma from nonneoplastic lymphocytes in LBC specimens.

Cytoplasmic Lipid Accumulation Characteristic of the Cribriform Variant of Papillary Thyroid Carcinoma

Objective: The purpose of this study was to clarify the diagnostic significance of cytoplasmic lipid accumulation (CLIA) in the cribriform variant of papillary thyroid carcinoma (CV-PTC). Methods: We performed a histological, immunohistochemical, and cytological examination of 35 CV-PTC cases at the Kuma Hospital. CLIA was defined as bubble-like multivacuolation in cytoplasm with distinct cell border. We also examined 100 conventional PTC (con-PTC) cases as controls. Results: Histological analysis showed the presence of carcinoma cells with CLIA in 60.0% of CV-PTC and 5.0% of con-PTC cases. The vacuoles tended to distribute in the subnuclear portion of carcinoma cells showing papillary growth. They were positive for oil red O staining and adipophilin. The carcinoma cells without the vacuoles showed a subnuclear dot-like expression for adipophilin in CV-PTC cases, but not in the con-PTC cases. Cytological analysis showed CLIA in 17 (54.8%) of the 31 CV-PTC cases, but not in the con-PTC cases. Conclusion: This is the first study to report the presence of carcinoma cells with CLIA in CV-PTC. The subnuclear dot-like expression of adipophilin may be characteristic of CV-PTC. These findings might be related to degenerative changes occurring in CV-PTC.