Follicular adenoma with a papillary architecture originating from an ectopic thyroid gland: a case report

BACKGROUND

Follicular adenomas with papillary architecture are rare tumors of thyroid origin and are composed of completely encapsulated follicular cells with a papillary architecture lacking the nuclear characteristics of papillary carcinoma. Herein, we present a case of follicular adenoma with papillary architecture originating from an ectopic thyroid gland, diagnosed from a mass in the submandibular region.

CASE PRESENTATION

A 70-year-old woman was referred to our hospital with the chief complaint of a painless left submandibular mass that had been present for one year. The patient underwent left submandibular dissection for therapy and diagnosis. Microscopically, papillary lesions with fibrovascular cores were observed in the interior, and the epithelial cells were cylindrical in shape with eosinophilic cytoplasm, round or oval nuclei, with no pathological features, leading to a diagnosis of papillary carcinoma or follicular carcinoma. The mass was diagnosed as a follicular thyroid adenoma with papillary architecture. This is the first report of a follicular adenoma with a papillary architecture originating from an ectopic thyroid gland.

CONCLUSION

This experience suggests that follicular adenoma should be included in the differential diagnosis of ectopic thyroid tumors.

An attempt to reduce unnecessary surgical procedures... Can ultrasound characteristics help in differentiating adenoma vs carcinoma in follicular thyroid neoplasms?

INTRODUCTION AND OBJECTIVES

Thyroid nodules frequently require ultrasound and Fine Needle Aspiration Cytology (FNAC) evaluation. However, FNA cytology does not allow differentiation between follicular adenoma and carcinoma on Bethesda type IV lesions. This situation leads to many unnecessary surgical procedures because it is not possible to assure the benignity of the lesions, even when most of the specimens correspond to adenomas or even other benign lesions. The objective is this study is to establish if there are any US characteristics that would help us to predict the risk of malignancy of nodules with a pathological diagnosis of follicular neoplasm in order to achieve a more conservative management for non-suspicious nodules.

MATERIAL AND METHODS

We studied 61 nodules in 61 patients (51 women and 10 men) that underwent thyroid surgery and had histopathological results of either follicular adenoma or carcinoma. Different US characteristics of the nodules were analysed (composition, echogenicity, margin, calcification status, the presence of halo and overall observer suspicion of malignancy) and were correlated with the histopathological analysis.

RESULTS

We have found a statistically significant association between the presence of calcifications, ill-defined borders and overall observer suspicion or impression (defined by well-known suspicious for malignancy ultrasonographic features, such as calcification, poorly defined margin, and a markedly hypoechoic solid nodule; and benign ultrasonographic features, such as predominantly cystic echogenic composition and the presence of a perinodular hypoechogenic halo) with follicular carcinoma. However all those features have shown low sensitivities in the present study (30%, 30% and 50%, respectively). On the other hand, the absence of halo sign has shown a sensitivity of 100% and a negative predictive value (NPV) of 100% in our study.

CONCLUSIONS

The presence of calcifications, ill-defined borders and the overall impression or suspicion of malignancy associate with a higher risk for follicular carcinoma in Bethesda type IV thyroid nodules but their absence do not allow to predict benignity in these nodules. Inversely, when a halo sign lesion is observed, benign follicular neoplasm should be considered.

DICER1 Mutations Occur in More Than One-Third of Follicular-Patterned Pediatric Papillary Thyroid Carcinomas and Correlate with a Low-Risk Disease and Female Gender Predilection

Some pediatric papillary thyroid carcinoma (PPTC) cohorts have suggested a preliminary correlation with respect to DICER1 mutation status and histomorphology in both benign and malignant follicular cell-derived nodules; however, the data regarding correlates of DICER1-related sporadic PPTCs subtyped based on the 2022 WHO classification criteria are largely unavailable. The current study investigated the status of hotspot DICER1 mutations with clinical, histological and outcome features in a series of 56 patients with PPTCs with no clinical or family history of DICER1-related syndromic manifestation. Fifteen (27%) PPTCs harbored BRAF p.V600E. Eight (14%) cases of PPTCs harbored DICER1 mutations with no associated BRAF p.V600E. DICER1 mutations were identified in exons 26 and 27. A novel D1810del (c.5428_5430delGAT) mutation was also detected. We also confirmed the absence of hotspot DICER1 mutations in the matched non-tumor tissue DNA in all 8 DICER1-related PPTCs. The mean age of DICER1-harboring PPTCs was 15.1 (range: 9-18) years whereas the rest of this cohort had a mean age of 14.8 (range 6-18) years. With the exception of one PPTC, all DICER1-related PPTCs were seen in females (female-to-male ratio: 7). The female to male ratio was 3.8 in 48 DICER1-wild type PPTCs. In terms of histological correlates, 5 of 8 (63%) DICER1-mutant PPTCs were invasive encapsulated follicular variant papillary thyroid carcinomas (FVPTCs) including 4 minimally invasive FVPTCs and 1 encapsulated angioinvasive FVPTC, whereas the remaining 3 PPTCs were infiltrative classic papillary thyroid carcinomas (p < 0.05). The incidence of DICER1 mutations was 19.5% in BRAF p.V600E-wild type PPTCs. Sixty-three percent of DICER1 hotspot mutations occurred in invasive encapsulated FVPTCs, and this figure represents 38% of invasive encapsulated FVPTCs. Only one (12%) patient with DICER1-related disease showed a single lymph node with micro-metastasis. Unlike DICER1-wild type patients, no distant metastasis is identified in patients with DICER1-related PPTCs. The current series expands on the surgical epidemiology of somatic DICER1-related PPTCs by correlating the mutation status with the clinicopathological variables. Our findings underscore that female gender predilection and enrichment in low-risk follicular-patterned PTCs are characteristics of DICER1-related PPTCs.

Diagnostic pitfall of thyroid fine-needle aspiration induced fibrosis: follicular adenoma mimicking medullary thyroid carcinoma in frozen section

Background

Fine-needle aspiration (FNA) is a frequently utilized method for the diagnosis of thyroid nodules. Although the technique has clear advantages, the injury caused by the aspiration needle can induce various histological alterations. Herein, we report a case of follicular adenoma showing histological alterations possibly caused by FNA biopsy. Furthermore, the histological appearance of the lesion mimicked those of medullary thyroid carcinoma, particularly in the frozen section.

Case presentation

Ultrasonography of a thyroid nodule in a 39-year-old man revealed a mass (2.2 cm in diameter) in the right thyroid lobe. FNA was performed three times on the mass, and the results of the cytology were atypia of undetermined significance. Thereafter, the patient underwent right hemithyroidectomy. The histological findings of the operative frozen section analysis indicated medullary thyroid carcinoma. However, after evaluation and immunohistochemical staining of the permanent section, the mass was diagnosed as follicular adenoma with extensive fibrosis.

Conclusion

The histological alterations observed in the follicular adenoma are believed to have been caused by injury during the repeated FNA procedures.

An attempt to reduce unnecessary surgical procedures... Can ultrasound characteristics help in differentiating adenoma vs carcinoma in follicular thyroid neoplasms?

INTRODUCTION AND OBJECTIVES

Thyroid nodules frequently require ultrasound and Fine Needle Aspiration Cytology (FNAC) evaluation. However, FNA cytology does not allow differentiation between follicular adenoma and carcinoma on Bethesda type IV lesions. This situation leads to many unnecessary surgical procedures because it is not possible to assure the benignity of the lesions, even when most of the specimens correspond to adenomas or even other benign lesions. The objective in this study is to establish if there are any US characteristics that would help us to predict the risk of malignancy of nodules with a pathological diagnosis of follicular neoplasm in order to achieve a more conservative management for non-suspicious nodules.

MATERIAL AND METHODS

We studied 61 nodules in 61 patients (51 women and 10 men) that underwent thyroid surgery and had histopathological results of either follicular adenoma or carcinoma. Different US characteristics of the nodules were analysed (composition, echogenicity, margin, calcification status, the presence of halo and overall observer suspicion of malignancy) and were correlated with the histopathological analysis.

RESULTS

We have found a statistically significant association between the presence of calcifications, ill-defined borders and overall observer suspicion or impression (defined by well-known suspicious for malignancy ultrasonographic features, such as calcification, poorly defined margin, and a markedly hypoechoic solid nodule; and benign ultrasonographic features, such as predominantly cystic echogenic composition and the presence of a perinodular hypoechogenic halo) with follicular carcinoma. However all those features have shown low sensitivities in the present study (30%, 30% and 50%, respectively). On the other hand, the absence of halo sign has shown a sensitivity of 100% and a negative predictive value (NPV) of 100% in our study.

CONCLUSIONS

The presence of calcifications, ill-defined borders and the overall impression or suspicion of malignancy are associated with a higher risk for follicular carcinoma in Bethesda type IV thyroid nodules but their absence does not allow to predict benignity in these nodules. Inversely, when a halo sign lesion is observed, benign follicular neoplasm should be considered.

Prevalence and diagnostic significance of noninvasive follicular thyroid neoplasm with papillary-like nuclear features among tumors previously diagnosed as follicular adenoma: a single-institutional study in Japan

The incidence of noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) in papillary thyroid carcinoma (PTC) is significantly lower in Asian countries than Western countries; however, the difference remains unexplained. This study aimed to evaluate the incidence of NIFTP in tumors diagnosed as follicular adenoma (FA) in a Japanese institution and discuss the significance of NIFTP. In this study, 44 tumors were investigated, which were histologically diagnosed as FA at the Kuma Hospital in 2008. Of the 44 tumors, 13 (29.5%) were revised as NIFTP. In the remaining 31 tumors, the FA diagnosis was reconfirmed. On aspiration cytology, most of the NIFTPs were categorized into follicular neoplasm or suspicious for a follicular neoplasm. On histological examination, 9 (29.0%) of 31 FA nodules showed a nuclear score of 1. Twelve (92.3%) of 13 NIFTP nodules showed a nuclear score of 2, and the remaining nodule had a nuclear score of 3. No metastasis of FA or NIFTP was detected. There were no evidences of distant metastasis during follow-up. This is the first study to describe that NIFTP is more frequently included in tumors diagnosed as FA rather than PTC in Japan. As clinical management of FA and NIFTP is the same, in Japan, there is no reason to distinguish between FA and NIFTP. Conclusively, the necessity of using the disease entity "NIFTP" is not found in Japan.

Ectopic intrapulmonary follicular adenoma diagnosed by surgical resection

Ectopic intrapulmonary thyroid tissue is extremely rare and considerably difficult to diagnose without surgery. Ectopic thyroid tissue, described as a mediastinal tumor, and intrapulmonary lesions are infrequent. An abnormal shadow was detected upon chest X-ray in a 60-year old woman with a history of benign thyroid goiter. A computed tomography scan revealed a solitary nodule measuring 27 mm in diameter in the left lower lobe, the diameter of which had increased by 5 mm since initial observation eight years ago. A thoracoscopic wedge resection was performed and the lesion was determined to be a non-invasive, soft-tissue tumor. It was pathologically diagnosed as an ectopic thyroid follicular adenoma. The course of the tumor was uneventful. A diagnosis of ectopic intrapulmonary thyroid should be made cautiously and only after ruling out metastasis of a follicular adenoma or thyroid carcinoma. This diagnosis of ectopic thyroid tissue was made possible by the surgical approach.

Evaluation of Diagnostic Utility of Immunohistochemistry Markers of TROP-2 and HBME-1 in the Diagnosis of Thyroid Carcinoma

OBJECTIVE

The diagnosis of thyroid tumors is based on histologic features, but the distinction between benign and malignant thyroid lesions is somehow difficult, especially in lesions with a follicular pattern. Thus, ancillary studies, such as immunohistochemistry (IHC), may be helpful. In this study, we aimed to evaluate the diagnostic value of 2 IHC markers, TROP-2 and HBME-1, in the diagnosis of thyroid cancers.

STUDY DESIGN

A total of 102 cases of thyroid lesions, including papillary thyroid carcinoma (classic variant) (29 cases), follicular variant of papillary thyroid carcinoma (21 cases), multinodular goiter (22 cases), follicular adenoma (24 cases), and follicular carcinoma (6 cases) were selected. The hematoxylin-eosin slides were reviewed for confirmation of diagnosis, and IHC examination for TROP-2 and HBME-1 was performed.

RESULT

HBME-1 had 84% sensitivity and 98% specificity with a positive predictive value (PPV) of 98% and a negative predictive value (NPV) of 83%. TROP-2 had 93% sensitivity and 74% specificity with a PPV of 81% and an NPV of 90% in malignant thyroid lesions.

CONCLUSION

IHC panel consisting of TROP-2 and HBME-1 can be used in equivocal follicular patterned lesions for the diagnosis of thyroid carcinomas.

Encapsulated Follicular Variant of Papillary Thyroid Carcinoma Arising in a Follicular Adenoma: a Diagnostic Dilemma

Papillary thyroid carcinoma (PTC) arising within follicular adenoma is a rare histological subset of papillary carcinoma. A 24-year-old female (euthyroid and asymptomatic) presented with a solitary mass in the right lobe of thyroid for 2 years. Fine-needle aspiration cytology (FNAC) suggested features of hyperplasia of thyroid. Hemithyroidectomy was performed. Histopathological examination revealed two distinct areas and was reported as encapsulated variant of papillary carcinoma along with follicular adenoma. Papillary carcinoma was confirmed by positive immunohistochemistry for HBME-1. CT head and neck region ruled out metastasis and the patient was kept on follow-up. There have been reports of medullary and papillary carcinomas occurring together; however, there is a paucity of literature on co-existing follicular neoplasm and papillary carcinoma. We hereby report a rare case of follicular variant of papillary carcinoma arising within follicular adenoma of the thyroid.

Methylation markers differentiate thyroid cancer from benign nodules

PURPOSE

The incidence of thyroid cancer (TC) is increasing. Cytology by itself cannot distinguish TC from some benign nodules especially in certain subtypes of TC. Our immediate goal is to identify DNA methylation markers for early detection of TC and to molecularly differentiate TC subtypes from benign nodules.

METHODS

Promoter methylation status of 21 candidate genes was examined on formalin-fixed paraffin-embedded tissue (FFPE) utilizing quantitative methylation-specific polymerase chain reaction (QMSP) in a retrospective cohort of 329 patients (56% white, 29% African American, 61% female) comprising 71 normal thyroid, 83 benign nodules [follicular adenomas (FA)], 90 follicular TC (FTC) and 85 papillary TC (PTC). All genes were analyzed individually (Kruskal-Wallis and Wilcoxon rank sum tests) and in combination (logistic regression models) to identify genes whose methylation levels might best separate groups.

RESULTS

Combination gene panels TPO and UCHL1 (ROC = 0.607, sensitivity 78%) discriminated FTC from FA, and RASSF1 and TPO (ROC = 0.881, sensitivity 78%) discriminated FTC from normal. Methylation of TSHR distinguished PTC from FTC (ROC = 0.701, sensitivity 84%) and PTC from FA (ROC = 0.685, sensitivity 70%). The six gene panel of TIMP3, RARB2, SERPINB5, RASSF1, TPO and TSHR, which differentiates PTC from normal thyroid, had the best combination sensitivity (91%) and specificity (81%) of the panels addressing discrimination of cancer tissue.

CONCLUSIONS

Aberrant gene methylation used in combination panels may be useful clinically in differentiating FTC and PTC from benign nodules. If confirmed in additional studies, these findings could help reduce the over diagnosis of thyroid cancer and surgeries related to over diagnosis.

Values of molecular markers in the differential diagnosis of thyroid abnormalities. J Cancer Res Clin Oncol. 2017;143:913-931. [PMID: 28008451 DOI: 10.1007/s00432-016-2319-9]

INTRODUCTION

Thyroid cancer (TC), follicular adenoma (FA) and Hashimoto's thyroiditis (HT) are three of the most frequently reported abnormalities that affect the thyroid gland. A frequent co-occurrence along with similar histopathological features is observed between TC and FA as well as between TC and HT. The conventional diagnostic methods such as histochemical analysis present complications in differential diagnosis when these abnormalities occur simultaneously. Hence, the authors recognize novel methods based on screening genetic defects of thyroid abnormalities as viable diagnostic and prognostic methods that could complement the conventional methods.

METHODS

We have extensively reviewed the existing literature on TC, FA and HT and also on three genes, namely braf, nras and ret/ptc, that could be used to differentially diagnose the three abnormalities. Emphasis was also given to the screening methods available to detect the said molecular markers.

RESULTS AND CONCLUSION

It can be conferred from the analysis of the available data that the utilization of braf, nras and ret/ptc as markers for the therapeutic evaluation of FA and HT is debatable. However, molecular screening for braf, nras and ret/ptc mutations proves to be a conclusive method that could be employed to differentially diagnose TC from HT and FA in the instance of a suspected co-occurrence. Thyroid cancer patients can be highly benefited from the screening for the said genetic markers, especially the braf gene due to its diagnostic value as well as due to the availability of personalized medicine targeted specifically for braf mutants.

Hürthle Cells Adenoma of the Thyroid with Post-surgical Implants in the Neck: Clinical, Morphological, and Molecular Analysis of Three Cases

Thyroid implants in the soft tissue of the neck are very rare findings of traumatic, iatrogenic, or neoplastic origins. We describe the clinico-pathological and molecular analysis of three cases with an initial diagnosis of follicular adenoma, Hürthle cell variant (FA-HCT), which developed cervical thyroid implants at 60, 59, and 36 months after thyroid surgery, followed by further neck recurrences, and, eventually, by distant metastases. A systematic review of all histopathological samples of both the primary lesions and the neck implants was performed. Molecular study included the analysis of pan-RAS and BRAF mutations and RET/PTC1, RET/PTC3, and PAX8/PPARγ rearrangements. The review of the original slides and of additional re-cuts of each block of the thyroid lesions did not show any sign of capsular and/or vascular invasion; thus, the original diagnoses of FA-HCT were confirmed. When sampling adequacy was considered, it turned out that the capsule was completely evaluable in case #3, whereas 85 % was evaluable for case #1 and less than 50 % for case #2. We cannot exclude that cases #1 and #2 were carcinomas that had not been completely sampled. The first occurring neck implants showed neither histological signs of malignancy nor the presence of lymphoid tissue. However, further neck recurrences had different histological aspects, with a clear infiltrative growth. Moreover, a mesenchymal reaction forming a sort of capsule was observed around oncocytic cells along with signs of vascular invasion. Molecular analysis revealed no alterations in the genes and rearrangements studied. Oncocytic thyroid implants in the neck soft tissue should be regarded as metastasis, even in the absence of clear-cut signs of malignancy and in the case of a bona fide diagnosis of Hürthle cells adenoma of the thyroid.

Ultrasonographic Differentiation Between Nodular Hyperplasia and Neoplastic Follicular-Patterned Lesions of the Thyroid Gland

We evaluate the gray-scale ultrasonographic characteristics that differentiate between nodular hyperplasia (NH) and neoplastic follicular-patterned lesions (NFPLs) of the thyroid gland. Ultrasonographic features of 750 patients with 832 thyroid nodules (NH, n = 361; or NFPLs, follicular adenoma, n = 123; follicular carcinoma, n = 159; and follicular variant papillary carcinoma, n = 189) were analyzed. Except for echogenicity, over two-thirds of the cases of NH and NFPLs share the ultrasonographic characteristics of solid internal content, a well-defined smooth margin and round-to-ovoid shape. Independent predictors for NH were non-solid internal content (sensitivity 27.1%, specificity 90.2%), isoechogenicity (sensitivity 69.5%, specificity 63.5%) and an ill-defined margin (sensitivity 18.8%, specificity 94.5%). Independent predictors for NFPLs were hypoechogenicity (sensitivity 60.5%, specificity 70.4%), marked hypoechogenicity (sensitivity 2.8%, specificity 99.4%) and taller-than-wide shape (sensitivity 6.6%, specificity 98.1%). Although NH and NFPLs commonly share ultrasonographic characteristics, non-solid internal content and ill-defined margin are specific to NH and marked hypoechogenicity and taller-than-wide shape are specific to NFPLs.

Detection of global hypermethylation in well-differentiated thyroid neoplasms by immunohistochemical (5-methylcytidine) analysis

PURPOSE

While global hypomethylation of DNA has been found in several malignancies, studies on thyroid tumours have shown controversial results using different techniques. To help resolve this issue, we assessed methylation status using two different techniques in papillary thyroid carcinomas (PTC) and follicular adenomas (FA) and carcinomas (FTC), comparing adjacent non-neoplastic thyroid tissue.

METHODS

A series of 15 FA, 18 FTC and 17 PTC were assessed by: (1) measurement of methylation levels of long interspersed nuclear elements (LINE-1) using a combined bisulfite restriction analysis polymerase chain reaction protocol and (2) immunostaining with an anti-5-methylcytidine antibody that detects methylated DNA regardless of the DNA sequence. Immunostaining was scored by image analysis.

RESULTS

Methylation levels of LINE-1 in FA, FTC and PTC were not significantly different from adjacent normal tissue. There was no significant difference in methylation levels of LINE-1 between FA, FTC and PTC (p = 0.44). By immunohistochemical staining for methylation, the 5-methylcytidine score was significantly higher in tumours than in normal tissue counterparts, for FA (p < 0.001), FTC (p = 0.04) and PTC (p = 0.02). PTC showed the highest 5-methylcytidine expression amongst all tumours which was significantly different from FTC (p = 0.015), but not FA (p = 0.09). There was no correlation in methylation level between LINE-1 and 5-methylcytidine scores for each group and overall.

CONCLUSIONS

Well-differentiated thyroid neoplasms (FA, FTC and PTC) were not found by two independent methods to undergo global hypomethylation as part of an oncogenic sequence from normal tissue to carcinoma. Instead, hypermethylation was detected in all types of tumours, implying that this epigenetic event may contribute to oncogenic development of thyroid neoplasms (both benign and malignant).

A case of asymptomatic riedel thyroiditis with follicular adenoma in a patient with a multinodular goiter: an unusual association

BACKGROUND

Riedel's thyroiditis (RT) is a rare inflammatory disease that results in fibrosis of the thyroid gland and invasion to the surrounding structures of the neck. Follicular adenoma (FA) of the thyroid is the most common benign neoplasm of the gland.

PATIENT FINDINGS

A 42-year-old woman was referred to the outpatient clinic due to a multinodular goiter and thyroiditis. The patient was euthyroid and thyroid function tests were within normal limits. Thyroid antibodies (thyroid peroxidase antibody and thyroglobulin antibody) were high. Thyroid ultrasonography showed multiple iso-hypoechoic nodules and thyroiditis. Fine-needle aspiration cytology was performed, and it was consistent with 'suspicious for a follicular neoplasm' according to the Bethesda system. Due to the clinical findings, which included weight loss and sweating, and the cytological results indicative of a follicular neoplasm, the patient underwent a total thyroidectomy. The histopathological diagnosis was RT associated with FA. The patient was started on thyroid hormone (thyroxine) replacement therapy after surgery and was evaluated for additional fibrosis related to RT.

CONCLUSIONS

To our knowledge, this is the first case of RT associated with FA in an asymptomatic patient with a multinodular goiter and high thyroid antibodies reported in the literature.