Galectin-3 expression in hyalinizing trabecular tumors of the thyroid gland

Diagnostic clues for hyalinizing trabecular tumor on fine needle aspiration cytology

Objectives

The hyalinizing trabecular tumor (HTT) is a rare benign neoplasm of the thyroid gland. This neoplasm has overlapping cytological features with Papillary Thyroid Carcinoma, Medullary Carcinoma and Follicular Neoplasm with Nuclear Features of Papillary Carcinoma. This can lead to misdiagnosis of malignancy in fine needle aspiration (FNA) cytology specimens with unnecessary total thyroidectomy. The aim of this study is to determine if there are some cytological features that could help us to suspect HTT on FNA specimens and avoid radical surgery.

Material and Methods

With this purpose we have collected 6 cases diagnosed of HTT in Hospital Clínico San Carlos of Madrid (Spain) in the last 10 years and reviewed the cytological specimens.

Result

We conclude that the presence of hyaline material in FNA specimens of HTT is a constant feature being a diagnostic clue. We must be cautious not to confuse it with dense colloid or amyloid material, the latter seen in Medullary Carcinoma. Papillary architecture and fibrovascular cores are not present in a HTT. Special stains as ki-67, calcitonin and Congo Red staining could help us in achieving the correct diagnosis.

Conclusion

We feel the cytopathologists must be aware of the distinguishing features of this lesion, mainly the typical hyaline material to achieve a proper diagnosis and be able to reduce unnecessary aggressive management of these patients.

The Diagnosis of Hyalinizing Trabecular Tumor: A Difficult and Controversial Thyroid Entity

Hyalinizing trabecular tumor (HTT) is a benign, follicular-derived neoplasm composed of thick trabeculae with round or elongated cells having irregular and clear nuclei, and containing intra-trabecular hyaline material. The cytological features of HTT resemble those of papillary carcinoma, which helps explain why these lesions are usually classified as indeterminate/suspicious according to the Bethesda system for reporting thyroid cytology. A review of the literature indicates that reaching the correct preoperative cytologic diagnosis of HTT remains elusive, as the correct interpretation was achieved in only 8% of cases. In contrast, the correct diagnosis posed a less significant diagnostic challenge in the majority of histological series, despite the reported controversy on the relationship of this tumor with papillary and medullary thyroid carcinomas. The aim of this review is to highlight the cytological and histological clues in the diagnosis of HTT, as well as its molecular profile.

Recent Advances in the Classification of Low-grade Papillary-like Thyroid Neoplasms and Aggressive Papillary Thyroid Carcinomas: Evolution of Diagnostic Criteria

Papillary thyroid carcinomas account for ∼80% of well-differentiated thyroid tumors. During the past decade, several new variants of papillary-like thyroid neoplasms and papillary thyroid carcinomas have been recognized. Some of these neoplasms that were previously classified as malignant have been reclassified as low-grade neoplasms, as the diagnostic criteria have evolved. Similarly, some of the papillary thyroid carcinomas that were previously classified as conventional or classic papillary thyroid carcinomas have now been recognized as more aggressive variants of papillary thyroid carcinomas. Recognizing these differences becomes more important for the proper medical, surgical, and radiotherapeutic management of patients with these neoplasms.

Hyalinizing Trabecular Tumor of the Thyroid Gland, a Diagnostic Challenge in Fine-Needle Aspiration Cytology: Case Report

Hyalinizing trabecular tumor (HTT) is a rare thyroid tumor with low to minimal malignant potential. HTT is often misinterpreted as other thyroid tumors, including papillary thyroid carcinoma (PTC) and medullary thyroid carcinoma (MTC), on fine-needle aspiration (FNA) cytology, because of its overlapping cytologic features, such as nuclear grooves and intranulcear pseudoinclusions. Although cytopathologists cannot definitely conclude HTT by FNA cytology, suspicion of HTT is necessary to avoid misdiagnosing HTT as PTC or MTC and to avoid unnecessary aggressive treatment. Here, we report a case of HTT with novel cytologic features in CellPrep liquid based cytology that was diagnosed as suspicious for papillary carcinoma by FNA and finally diagnosed as HTT in the surgical specimen.

Hyalinizing trabecular tumour of the thyroid: fine-needle aspiration cytological diagnosis and correlation with histology

Hyalinizing trabecular tumour (HTT) is a rare thyroid neoplasm of follicular cell origin characterised by a trabecular growth pattern and prominent intratrabecular and intertrabecular hyalinisation. These peculiar histological features allow the prompt recognition of this neoplasm in surgical specimens. However, cytological diagnosis of HTT remains elusive and misleading because of overlapping characteristics with other thyroid tumours, particularly papillary thyroid carcinoma (PTC), medullary thyroid carcinoma (MTC) and the newly described non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP). Nevertheless, the proper recognition of this neoplasm on preoperative cytological preparations is important to avoid unnecessary overtreatment of this indolent lesion. A thorough review of the literature has revealed that the correct diagnosis of HTT in cytological smears is achieved in only 8% of cases. In a further 6% of cases, diagnostic doubt has been indicated. Sixty percent of published cases of HTT have been misdiagnosed as suggestive, suspicious or positive for PTC. These findings underline the difficulties of a cytological-based diagnosis of such entity. In this article we review the cytomorphological features of HTT and their correlation to histological features to provide the reader with the tools to improve diagnostic performance in the identification of HTT on preoperative cytology.

Galectin-3 Immunohistochemical Expression in Thyroid Neoplasms

BACKGROUND

Galectin-3 has been implicated in the regulation of cellular growth, differentiation and malignant transformation in various organs including thyroid gland. It has been extensively studied as an immunohistochemical (IHC) marker in thyroid malignancy.

AIM

To evaluate the diagnostic role of Galectin-3 (Gal-3) in differentiating malignant from benign thyroid neoplasm.

MATERIALS AND METHODS

In this observational study we evaluated Gal-3 expression in a spectrum of malignant (30) and benign (20) thyroid neoplasms. The final common diagnosis arrived at after histopathologic evaluation of H&E stained sections by two pathologist's was considered the gold standard. The malignant neoplasms included Papillary Thyroid Carcinoma (PTC), Follicular Thyroid Carcinoma (FTC), Medullary Thyroid Carcinoma (MTC), insular carcinoma, Anaplastic Thyroid Carcinoma (ATC), and metastatic carcinoma. The benign neoplasms included Follicular Adenoma (FA), Hurthle cell adenoma and hyalinizing trabecular adenoma. IHC staining for Gal-3 was performed for all neoplasms with the polymeric method using lyophilized mouse monoclonal antibody.

STATISTICAL ANALYSIS

Statistical analysis was done using 2x2 contingency table. Chi-square test with Yates correction was used to calculate p-value to ascertain statistical significance.

RESULTS

Gal-3 expression was significantly higher in malignant thyroid neoplasms as compared to benign neoplasms (p<0.0001). Gal-3 expression in differentiating malignant from benign neoplasms was found to have sensitivity of 86%, specificity of 85%, positive predictive value of 89.66% and negative predictive value of 80.95%. However, no statistical significance was observed (p=0.4718) when comparing PTC and other malignant lesions in terms of Gal-3 expression. Gal- 3 expression in PTC was found to have sensitivity of 91.3%, specificity of 85%, positive predictive value of 87.5% and negative predictive value of 89.47%.

CONCLUSION

Diffuse and strong IHC staining for Gal-3 differentiates malignant from benign tumours. This marker can assist in the diagnosis of thyroid neoplasms with equivocal morphologic features. This study highlights the high sensitivity of Gal-3 for PTC.

Defining the value of CD56, CK19, Galectin 3 and HBME-1 in diagnosis of follicular cell derived lesions of thyroid with systematic review of literature

BACKGROUND

Nodular follicular lesions of thyroid gland comprise benign and malignant neoplasms, as well as some forms of hyperplasia. "Follicular" refers to origin of cells and in the same time to growth pattern - building follicles. Nodular follicular thyroid lesions have in common many morphological features, therefore attempts were made to define additional criteria for distinction between follicular adenoma, follicular carcinoma and follicular variant of papillary carcinoma. Increasing number of immunohistochemical markers is in the continual process of evaluation.

METHODS

Tissue microarrays incorporating, total 201 cases, out of which 122 malignant and 79 benign follicular lesions, including neoplastic and non-neoplastic, were constructed and immunostained with antibodies to CD56, CK19, Galectin-3, HBME-1. Tissue cores were exclusively being acquired from tumour/lesion on interface with normal thyroid tissue. A systematic review of literature was done for period from the year 2001 to present time.

RESULTS

All analysed markers may make a difference between benign lesions/tumours from differentiated thyroid carcinomas (p = <0.01, for all markers). Expression of all markers is significantly higher in papillary carcinoma than in follicular adenoma (p < 0.01). Statistically significant difference in expression of Galectin-3 and CD56 between follicular carcinoma and follicular adenoma was registered (p = 0.043; p = 0.028, respectively). The only marker which expression showed statistically significant difference between adenoma and carcinoma of Hurthle cells was Galectin 3 (p = 0.041). CK19 and HBME-1 were significantly expressed more in papillary carcinoma as compared to follicular carcinoma.

CONCLUSION

Galectin 3 is most sensitive marker for malignancy, while loss of expression of CD56 is very specific for malignancy. Expected co-expression for combination of markers in diagnosis of follicular lesions decreases sensitivity and increases specificity for malignancy.

The ultrasonography features of hyalinizing trabecular tumor of the thyroid gland and the role of fine needle aspiration cytology and core needle biopsy in its diagnosis

BACKGROUND

Hyalinizing trabecular tumor (HTT) of the thyroid gland is a rare, benign neoplasm of follicular cell origin. Misdiagnosis of HTT as either papillary or medullary thyroid carcinoma after fine-needle aspiration (FNA) may lead to unnecessary surgery.

PURPOSE

To evaluate the ultrasonography (US) findings of HTT of the thyroid gland and the role of FNA cytology and core needle biopsy (CNB) in its diagnosis.

MATERIAL AND METHODS

Data from 24 patients with a histopathological diagnosis of HTT between January 2000 and May 2013 were retrospectively analyzed. US findings were categorized according to shape, margin, orientation, echogenicity, composition, calcification, and vascularity. Cytologic and histologic results of FNA, CNB, and surgery were reviewed.

RESULTS

US revealed the following tumor features: oval-to-round (24/24), solid (22/24), smooth margin (21/24), hypoechoic or marked hypoechogenicity (18/24), and peri- and/or intranodular vascularity (17/17). Malignant US features such as marked hypoechogenicity (n = 7) and a spiculated margin (n = 3) were also observed. Final confirmation was by surgery in 22 patients and by CNB in two patients. All 19 patients who underwent FNA were initially misdiagnosed, including 12 with malignancies and five with atypia of undetermined significance. All four patients who underwent CNB were correctly diagnosed with HTT. The histology of CNB specimens suggested HTT, which was confirmed by immunostaining of MIB-1.

CONCLUSION

HTT should be suspected when the cytological diagnosis of papillary thyroid carcinoma is made after FNA without malignant US findings. CNB could prevent unnecessary surgery for HTT.

Application of Immunohistochemistry in Thyroid Pathology

Context

Accurate classification of follicular-patterned thyroid lesions is not always an easy task on routine surgical hematoxylin-eosin–stained or cytologic fine-needle aspiration specimens. The diagnostic challenges are partially due to differential diagnostic criteria that are often subtle and subjective. In the past decades, tremendous advances have been made in molecular gene profiling of tumors and diagnostic immunohistochemistry, aiding in diagnostic accuracy and proper patient management.

Objective

To evaluate the diagnostic utility of the most commonly studied immunomarkers in the field of thyroid pathology by review of the literature, using the database of indexed articles in PubMed (US National Library of Medicine) from 1976–2013.

Data Sources

Literature review, authors' research data, and personal practice experience.

Conclusions

The appropriate use of immunohistochemistry by applying a panel of immunomarkers and using a standardized technical and interpretational method may complement the morphologic assessment and aid in the accurate classification of difficult thyroid lesions.

Unusual thyroid tumors: a review of pathologic and molecular diagnosis

The most common thyroid neoplasms are either follicular derived (papillary, follicular and Hürthle cell lesions) or C-cell derived (medullary carcinoma). The diagnosis of these tumors can usually be made at the histologic level, with immunohistochemical stains necessary in some circumstances. Specific molecular mutations have been described that can be diagnostically useful or explain, in part, their pathogenesis, including the well-known Ret/PTC and PPARgamma-PAX8 translocations, point mutations in the Ret, Ras and BRAF genes, and loss of heterozygosity of multiple different tumor suppressor genes. Some unusual tumors of the thyroid gland are more difficult to diagnose. In examining these lesions, the pathologist may use the hematoxylin and eosin-stained morphology, coupled with an analysis of the immunohistochemical staining profiles and possibly analysis of the underlying molecular mutational patterns. These less common thyroid tumors include tall cell and cribriform-morular variants of papillary carcinoma, hyalinizing trabecular tumor, mucoepidermoid and sclerosing mucoepidermoid carcinoma with eosinophilia, poorly differentiated (insular) carcinoma, and undifferentiated (anaplastic) carcinoma. The diagnostic features of these rare tumors, including the histology, immunohistochemical expression profiles and the known molecular mutational profiles of each, are reviewed.

HBME-1 expression in hyalinizing trabecular tumours of the thyroid gland

AIMS

Hyalinizing trabecular tumour (HTT) is a rare thyroid neoplasm with a trabecular growth pattern, marked intratrabecular hyalinization and nuclear features of papillary thyroid carcinoma (PTC). Immunohistochemical HBME-1 expression was reported recently in PTC, but not in HTT. To clarify further the value of HBME-1 expression as a tool in differential diagnosis, we investigated the immunophenotype of HTT.

METHODS AND RESULTS

Eight HTT diagnosed from 1997 to 2012 were reviewed on H&E-stained tissue sections and analysed for HBME-1, galectin-3, CK19 and Ki67 expression by immunohistochemistry. Three of eight HTTs (37.5%) were HBME-1 positive, with staining of tumour cells as well as of intratrabecular hyaline matrix material. All cases were CK19 negative. Galectin-3 was expressed weakly in four of eight cases (50%). Five of eight cases (62.5%) showed weak-to-moderate cytoplasmic Ki67 positivity.

CONCLUSIONS

Immunohistochemical HBME-1 expression is present in HTT and may not serve as a reliable marker in differentiating HTT from PTC. The HBME-1 positivity of the hyaline matrix suggests that this material is partly of cytoplasmic origin.

[Hyalinizing trabecular tumor of the thyroid. An overcautious designation of a benign thyroid tumour?]

Hyalinizing trabecular tumours of the thyroid represent a rare entity of follicular cell derived tumours and are characterized by a marked intratrabecular hyalinisation. These tumours share architectural similarities with medullary thyroid carcinomas and exhibit nuclear features such as nuclear pseudoinclusions resembling papillary thyroid carcinoma. However, the clinical behaviour remains unclear. On the basis of their inconspicuous appearance and absence of invasion or recurrence during follow-up, the tumour was initially classified as an adenoma. Subsequently, molecular findings such as the detection of RET / PTC rearrangements in some hyalinizing trabecular tumours favoured the designation as a variant of papillary thyroid carcinoma. However, miRNA profiling of hyalinizing trabecular tumours compared with benign thyroid lesions and papillary thyroid carcinoma failed to demonstrate the characteristic up-regulation found in papillary thyroid carcinoma. This article summarizes conventional diagnostic criteria with supplementary information regarding molecular pathogenesis of hyalinizing trabecular tumours of the thyroid.

Expression of CK-19, galectin-3 and HBME-1 in the differentiation of thyroid lesions: systematic review and diagnostic meta-analysis

Background

To distinguish between malignant and benign lesions of the thyroid gland histological demonstration is often required since the fine-needle aspiration biopsy method applied pre-operatively has some limitations. In an attempt to improve diagnostic accuracy, markers using immunocytochemistry and immunohistochemistry techniques have been studied, mainly cytokeratin-19 (CK-19), galectin-3 (Gal-3) and Hector Battifora mesothelial-1 (HBME-1). However, current results remain controversial. The aim of the present article was to establish the diagnostic accuracy of CK-19, Gal-3 and HBME-1 markers, as well as their associations, in the differentiation of malignant and benign thyroid lesions.

Methods

A systematic review of published articles on MEDLINE and The Cochrane Library was performed. After establishing inclusion and exclusion criteria, 66 articles were selected. The technique of meta-analysis of diagnostic accuracy was employed and global values of sensitivity, specificity, area under the summary ROC curve, and diagnostic odds ratio (dOR) were calculated.

Results

For the immunohistochemistry technique, the positivity of CK-19 for the diagnosis of malignant thyroid lesions demonstrated global sensitivity of 81% and specificity of 73%; for Gal-3, sensitivity of 82% and specificity of 81%; and for HBME-1, sensitivity of 77% and specificity of 83%. The association of the three markers determined sensitivity of 85%, specificity of 97%, and diagnostic odds ratio of 95.1. Similar results were also found for the immunocytochemistry assay.

Conclusion

This meta-analysis demonstrated that the three immunomarkers studied are accurate in pre- and postoperative diagnosis of benign and malignant thyroid lesions. Nevertheless, the search for other molecular markers must continue in order to enhance this diagnostic accuracy since the results found still show a persistency of false-negative and false-positive tests.

Virtual slides

Http://www.diagnosticpathology.diagnomx.eu/vs/3436263067345159

Hyalinizing trabecular tumor of the thyroid: a case report

Hyalinizing trabecular tumor (HTT) of the thyroid is a rare neoplasm that was first described by Carney in 1987. It is a tumor of follicular derivation with peculiar nuclear, architectural, histochemical, and immunohistochemical features. We report a case of HTT in a 69-year-old woman with a mutinodular goiter. Since the clinical and ultrasonographic features were nonspecific, fine needle aspiration biopsy (FNAB) of the left lobe-dominant node was performed that resulted in an indeterminate cytologic diagnosis (category THY-3). The patient underwent total thyroidectomy, with a histologic diagnosis of HTT. We discuss the clinical and diagnostic approach, including the role of FNAB, and the pathologic features of HTT with special reference to the possible differential diagnosis. Total thyroidectomy or hemithyroidectomy represent adequate treatments, while radioiodine ablation is not standard. Although rare cases of malignant HTT have been documented, this tumor should be considered a benign neoplasm or, at most, a neoplasm of extremely low malignant potential. As a consequence, once this diagnosis is rendered, clinical management should be conservative, which may include a precautionary annual follow-up in order to exclude the very rare possibility of recurrence, as exceptionally reported.

Immunohistochemical subclassification of thyroid tumors with a prominent hyalinizing trabecular pattern

The purpose of this study was to evaluate the immunohistochemical characteristics of thyroid tumors with a prominent hyalinizing trabecular pattern (TTHTP). Immunohistochemical stains for thyroid transcription factor 1 (TTF-1), thyroglobulin, CD56, cytokeratin (CK) 19, galectin-3, and Ki-67 were performed on 16 cases of TTHTP. All TTHTPs were positive for TTF-1 and thyroglobulin, and nine cases expressed CD56 and Ki-67. Of these nine cases, seven satisfied the strict criteria of Carney, and four cases were positive for CK19 or/and galectin-3 and negative for Ki-67 and CD56. The remaining three cases had no Ki-67, CD56, CK19 or galectin-3 expression. All TTHTPs meeting the criteria of Carney were hyalinizing trabecular tumors (HTT), and TTHTPs which did not satisfy the criteria of Carney were subclassified according to the immunohistochemical results as the HTT type [Ki-67 (+) and CD56 (+)], papillary thyroid carcinoma (PTC) type [CK19 or galectin-3 (+)/Ki-67 (-) and CD56 (-)], or null type [Ki-67 (-), CD56 (-), CK19 (-) and galectin-3 (-)]. TTHTPs with typical histologic features and/or with typical immunohistochemical manifestations can be categorized as HTT, and the remaining TTHTPs should be categorized as the PTC or null type.

Diagnostic dilemmas of hyalinizing trabecular tumours on fine needle aspiration cytology: a study of seven cases with BRAF mutation analysis

OBJECTIVE

Hyalinizing trabecular tumours (HTTs) are rare follicular-derived neoplasms that behave in an almost benign manner. HTT is frequently misdiagnosed as papillary carcinoma by fine needle aspiration (FNA) cytology or as papillary or medullary carcinoma on surgical resection.

METHODS

The authors examined FNA material from seven cases of histologically verified HTT. Cytological findings were reviewed and correlated with ultrasonographic and histological features. In addition, MIB-1 and calcitonin immunostaining was performed on surgical specimens, and BRAF mutation analysis on three pre-operative FNA specimens and seven histology specimens.

RESULTS

The original cytological diagnosis was either suspicious or positive for papillary carcinoma in all patients. The FNA-based differential diagnoses included HTT, papillary carcinoma or, less likely, medullary carcinoma in two patients. Aspirates showed oval to spindle-shaped cells with frequent intranuclear inclusions, isolated in loosely cohesive groups with a trabecular or syncytial pattern in a bloody background. Radiating arrangements of tumour cells surrounding hyaline stroma with serrated calcifications and a lack of papillary or sheet-like fragments may suggest HTT on FNA. Spherical calcified bodies and possible psammoma bodies were frequently found in three cases. Retrospectively, six of the seven cases showed membranous immunoreactivity for MIB-1, but none of the seven possessed the BRAF (V600E) mutation or showed calcitonin reactivity.

CONCLUSIONS

Although the recognition of HTT on FNA cytology is difficult, because of its morphological similarities to papillary and medullary carcinoma, its characteristic cytological features along with ultrasonographic findings may suggest the diagnosis preoperatively and avoid surgical over-treatment.

Hyalinizing trabecular tumors of the thyroid gland are almost all benign

In 1987, Carney et al reported 11 thyroid tumors with the following features: circumscription or encapsulation, trabecular architecture with intratrabecular hyalin and colloid, polygonal and spindle cells, nuclei with frequent grooves and cytoplasmic inclusions, occasional psammoma bodies, and a low mitotic rate. The neoplasms did not recur or metastasize during a follow-up period that averaged 10 years, and they were titled hyalinizing trabecular adenomas. Subsequently, the nuclear features of the neoplasm led to the introduction of 2 modified titles for it, hyalinizing trabecular tumor and hyalinizing trabecular neoplasm. Later, discovery of RET/PTC mutations in the tumor resulted in it being designated as a type of papillary thyroid carcinoma. We studied 119 neoplasms of the type outlined, collected over a 20-year period, for invasion, recurrence and metastasis, and obtained follow-up in 96% of the cases. One hundred eighteen tumors showed no evidence of aggressive behavior (capsular, vascular, and parenchymal invasion), local recurrence, or metastasis. One tumor showed vascular and capsular invasion, and pulmonary metastasis. We conclude that the overwhelming majority of hyalinizing trabecular tumors of the thyroid behave as benign neoplasms and that, at this time, hyalinizing trabecular adenoma is the most appropriate title for them.

Potential diagnostic markers in nodular lesions of the thyroid gland: an immunohistochemical study

AIMS

The differential diagnosis of thyroid nodules in routine practice can be problemmatic for both pathologists and clinicians. Effective treatment requires a determination of the biological nature of the lesions. For this reason, ancilliary diagnostic markers along with histological examination of the nodules may be useful. The objective of this study was to evaluate the diagnostic usefulness of novel markers in the diagnosis of hyperplastic and neoplastic nodules.

METHODS

Forty eight thyroid lesions forming four diagnostic groups including adenomatous goiters (AS), follicular adenomas (FA), follicular (FC) and papillary carcinomas (PC) were examined using standard immunohistochemical methods. Monoclonal antibodies against galectin-3, matrix metalloproteinases (MMPs) -2 and -7 and endothelial markers CD31 and CD105 were used.

RESULTS

The cytoplasmatic expression of galectin-3 was positive in all cases of papillary carcinoma. Moreover, statistically significant differences between fused groups of benign (AS and FA) and malignant lesions (FC and PC) were found Fischer's exact test (p = 0.0001). No significant differences in cytoplasmic expression of MMPs -2 and -7 and in vascular density assessed by using of both endothelial markers between benign lesions and malignant tumors were revealed.

CONCLUSIONS

Galectin-3 appears to be a useful marker in the diagnosis of papillary carcinoma only. The matrix metalloproteinases-2 and -7 are not helpful in distinguishing hyperplastic and neoplastic thyroid nodules. Endothelial markers do not appear to be suitable for thyroid differential diagnosis. A panel of antibodies in the differential diagnosis of thyroid nodular lesions would seem most suitable and further studies with larger sets of patients are awaited.

A case of black thyroid associated with hyalinizing trabecular tumor

Black thyroid is an uncommon phenomenon of black pigmentation of thyroid parenchyma induced by chronic minocycline therapy. Thyroid tumors associated with black pigmented thyroid are rare. We describe here a 42-year-old woman with a black thyroid associated with hyalinizing trabecular tumor (HTT). The patient presented with a palpable left-sided thyroid nodule. She had taken minocycline for aphthous stomatitis and an oral ulcer for 9 years. The findings of fine needle aspiration biopsy and BRAF mutation analysis suggested a papillary carcinoma. The patient underwent a near-total thyroidectomy with central compartment node dissection. The surgical specimen showed a diffuse black thyroid and a 2-cm non-pigmented, well-circumscribed nodule in the left thyroid. Histopathologically, numerous black pigmented follicular epithelial cells and colloid were seen throughout the thyroid parenchyma, and the nodule was composed of elongated, polygonal cells in trabecular arrangement and dense hyaline stromas. The tumor cells showed a strong positive cytoplasmic reaction to Ki 67. All of these findings suggested a HTT, or a hyalinizing trabecular variant of papillary carcinoma, arising in a black thyroid. To our knowledge, this is the first case of black thyroid associated with HTT.

Hyalinizing trabecular tumors of the thyroid gland: quadruply described but not by the discoverer

Hyalinizing trabecular tumors of the thyroid have been described on 4 occasions, by Carney and colleagues in 1987, by Ward and coworkers in 1982, by Pierre Masson in 1922, and by Rahel Zipkin in 1905. Zipkin credited her chief, Theodor Langhans (of Langhans giant cell fame), with identification of the cases she reported. Unaware of the 3 earlier descriptions, Carney and colleagues described 11 circumscribed or encapsulated thyroid tumors with elongated and polygonal cells arranged in trabeculae that contained a hyaline material resembling amyloid. The nuclei of the tumor cells had cytoplasmic invaginations and grooves similar to those of papillary carcinoma. Carney and colleagues labeled the neoplasms hyalinizing trabecular adenomas because of their microscopic appearance, absence of invasion, and benign natural history. Subsequently, the nuclear features of the tumor and the molecular genetic findings led to the introduction of equivocal designations for it, hyalinizing trabecular tumor and hyalinizing trabecular neoplasm, and later to its designation as a variant of papillary carcinoma. Experience has shown that most circumscribed or encapsulated follicular thyroid tumors with intratrabecular hyalin and nuclear features of papillary carcinoma behave as benign neoplasms. Hyalinizing trabecular carcinoma is a very rare tumor.

Hyalinizing trabecular tumor of the thyroid: an update

Hyalinizing trabecular tumor (HTT) is a rare thyroid tumor of follicular cell origin with a trabecular pattern of growth and marked intratrabecular hyalinization. This tumor is known to share morphological and architectural similarities with paraganglioma and medullary thyroid carcinoma, as well as the nuclear features and RET/PTC1 translocations of papillary thyroid carcinoma. These tumors are not associated with RAS or BRAF mutations. Whether the presence of RET alterations in HTT are sufficient molecular proof of its relationship with papillary thyroid carcinoma (PTC) is still to be defined. Of great interest is the characteristic strong peripheral cytoplasmic and membranous staining of the tumor cells with MIB1 immunostain, not seen in any other thyroid neoplasm. Although cases of malignant HTT have been recorded, HTT should be considered a benign neoplasm or, at most, a neoplasm of extremely low malignant potential.

Hyalinizing trabecular adenoma—an uncommon thyroid tumor frequently misdiagnosed as papillary or medullary thyroid carcinoma

BACKGROUND

Hyalinizing trabecular adenoma (HTA) is an uncommon benign thyroid tumor that can present as a solitary thyroid nodule, a prominent nodule in a multinodular goiter, or as an incidental finding in a thyroidectomy specimen. The clinical significance of the lesion is that it is frequently misdiagnosed as papillary carcinoma on fine-needle aspiration cytology or as papillary or medullary carcinoma on histopathological section. We reviewed our recent experience with 7 patients diagnosed with HTA.

METHODS

Fine-needle aspiration biopsy was performed in 7 patients presenting with a solitary thyroid nodule (n = 4) or a multinodular goiter (n = 3). The patients underwent total thyroidectomy (n = 6) or hemithyroidectomy (n = 1).

RESULTS

In 4 patients, the preoperative cytology was suggestive of papillary carcinoma, in 2 patients suspicious, and in 1 patient positive for papillary carcinoma. On histopathological section, 2 patients had a microscopic HTA, 2 patients had HTA in 1 or 2 nodules of a multinodular goiter, and 3 patients had HTA in a solitary nodule. Except in 1 patient, who had a microscopic focus (3.2 mm) of papillary carcinoma, there was no evidence of malignancy in the surgical specimens on permanent histopathological section.

CONCLUSIONS

Although HTA is a rare condition of the thyroid, the surgeon needs to be aware of this entity to be able to better discuss the pathological findings with the patient, particularly since some pathologists and endocrinologists believe that HTA may represent a malignant neoplasm of low metastatic potential.

[Galectin-3 immunodetection in thyroid fine-needle aspirates: technical procedure and results]

Fine-needle aspiration cytology of thyroid nodules is an excellent diagnostic tool. However, in about 20% cases of the so-called undeterminate lesions, cytological findings are inconclusive as distinction between benign from malignant lesions is difficult. Less than 20% of such undeterminate lesions will be malignant after histological diagnosis. Several molecular markers of thyroid malignancy are under investigation, among them Galectin-3. Here we present a study of this marker performed on fine-needle aspiration samples including description of an easy to implement technical procedure.

Hyalinizing Trabecular Adenoma of the Thyroid Revisited: A Histologic and Immunohistochemical Study of Thyroid Lesions With Prominent Trabecular Architecture and Sclerosis

BACKGROUND

Since its description, hyalinizing trabecular adenoma (HTA) of the thyroid has been a controversial entity. Some have considered it a unique entity, some have considered it a variant of papillary carcinoma (PC), and still others have considered it a nonspecific pattern that may be seen with a variety of thyroid lesions. Complicating the matter, studies demonstrating metastases have shown entities that do not appear to be HTAs as originally described, and molecular studies showing changes of PC have used methods that are not specific. This study reviews our experience with thyroid lesions that showed at least some histologic features of HTA and presents the immunohistochemical findings for these lesions using antibodies employed for the diagnosis of PC.

DESIGN

Our files were reviewed for all thyroid resection reports describing lesions with hyalinized or sclerotic stroma and a trabecular architecture within the diagnosis or diagnostic comment. All cases were reviewed and classified as either HTA or as different lesions based upon histologic features. Immunohistochemistry with antibodies to HBME1, CK19 and p63 was performed with all lesions and with a series of controls.

RESULTS

Eighteen thyroid lesions with prominent sclerosis or hyalinization and trabecular architecture were identified. Only 4 of these were found to completely match the histologic and cytologic descriptions of HTA by HE review. The other cases showed histologic features more compatible with other diagnoses including cellular adenomatoid nodule (5), follicular adenoma (4), follicular variant of PC (FVPC) (3), and epithelial neoplasm with features of FVPC (2). All HTAs lacked immunoreactivity for HBME1, CK19 and p63. All cases deemed to be adenomatoid nodules, follicular adenomas and epithelial neoplasms showed no immunoreactivity for HBME1 and CK19 and, of these, only a single AN showed immunoreactivity for p63. Cases deemed to be FVPCs showed diffuse immunoreactivity for HBME1 and CK19 and 1 reacted with antibodies to p63. Of control PCs and other thyroid lesions, reactivity for HBME1, CK19, and p63 was observed in 8/8, 7/7, and 7/8 and 3/27, 7/27, and 7/27 cases, respectively.

CONCLUSIONS

A sclerotic or hyalinized stroma with a trabecular growth pattern may be seen in a number of different thyroid lesions and, when seen, is usually a focal feature of a lesion other than HTA. Immunohistochemistry may be of assistance as cases of FVPC with prominent hyalinization and trabeculation will show immunoreactivity for HBME1 and CK19, whereas HTAs and other thyroid lesions with hyalinization and trabeculation will not.

Usefulness of HBME-1, cytokeratin 19 and galectin-3 immunostaining in the diagnosis of thyroid malignancy

AIMS

To investigate the usefulness of immunohistochemical expression and immunolocalization of a panel of thyroid malignancy markers including HBME-1, cytokeratin (CK) 19 and galectin-3.

METHODS AND RESULTS

We evaluated 170 thyroid lesions including 148 neoplastic lesions [84 papillary carcinomas (PC), 38 follicular carcinomas (FC), 18 follicular adenomas, one hyalinizing trabecular tumour, five medullary carcinomas, two anaplastic carcinomas] and 22 non-neoplastic lesions (12 adenomatous nodules and 10 Hashimoto's thyroiditis). HBME-1, galectin-3 and CK 19 were expressed in 94%, 72.6%, 72.6% of PCs and in 63%, 21%, 21% of FCs. The three markers were mostly negative in all normal tissues. Although the most helpful marker in terms of sensitivity and specificity for the follicular variant of PC and for FC diagnosis was HBME-1, when we consider the differentiation between cases of follicular variant of papillary carcinoma (FVPC) and FC or adenoma, in terms of percentage of positive cells, galectin-3 and CK 19 were more relevant.

CONCLUSIONS

HBME-1 is the most sensitive marker for thyroid malignancy but the three markers may be useful in specific cases. This panel of markers is useful to differentiate the follicular patterned lesions, with special reference to the FVPC.

Molecular profile of hyalinizing trabecular tumours of the thyroid: high prevalence of RET/PTC rearrangements and absence of B-raf and N-ras point mutations

Hyalinizing trabecular tumour (HTT) of the thyroid is a neoplasm of follicular derivation that shares several morphological similarities with papillary thyroid carcinoma (PTC). In this study, we investigated the prevalence of B-raf point mutations, RET/PTC rearrangements and N-ras point mutations in a large HTT series (28 samples). Twenty benign thyroid lesions and 10 PTC served as control cases. A high (47%) prevalence of RET/PTC rearrangements was found in HTT. By contrast, neither B-raf nor N-ras mutations were found in HTT. These findings suggest that, although RET/PTC, N-ras, and B-raf proteins may act along the same signalling cascade, the biological and morphological outcome of their oncogenic activation is not completely overlapping. Thus, in clinical practice, the detection of B-raf mutations in a thyroid follicular tumour may prove to be a valuable tool, supplementing histological examination, and allowing a differential diagnosis between PTC and HTT.

Human galectin-3 immunoexpression in thyroid follicular adenomas with cell atypia

Human galectin-3 (hgal-3) is a beta-galactoside binding protein involved in a number of physiological and pathological processes. Increasing hgal-3 immunoexpression has been reported in several human tumors, including thyroid carcinomas, but not in benign thyroid lesions. We analyzed the immunolocalization of hgal-3 in cell compartments of benign and malignant thyroid lesions. Hgal-3 immunoperoxidase reaction was carried out on 133 thyroid tissue samples obtained from 113 patients; 20 of these were normal (NT), 85 were benign thyroid lesions [20 colloid nodules (CN), 21 nodular hyperplasias (NH), 7 focal lymphocytic thyroiditis (FLT), 15 Hashimoto's thyroiditis (HT), 22 follicular adenomas (FA)], 25 differentiated carcinomas [15 papillary carcinomas (PC), 6 follicular carcinomas (FC) and 4 Hürthle cell carcinomas (HC)] and 3 anaplastic carcinomas (AC). Among the malignant thyroid lesions, hgal-3 was detected in 12/15 (80%) PC, 3/4 (75%) HC and in 4/6 (66.6%) FC, but in none of the 3 AC. Conversely, hgal-3 immunoexpression was absent in NT and in all benign thyroid lesions, but 1/15 HT and 10/22 (45.4%) FA. In the latter, hgal-3 was mostly expressed in microfollicular areas and in five of the six atypical FA. Hgal-3 cytoplasmic-perinuclear immunolocalization was observed in the majority of thyroid carcinomas and in more than half of the FA, theoretically suggesting an involvement of this protein in thyroid tumorigenesis throughout an antiapoptotic activity. Moreover, hgal-3 expression in FA might anticipate the likelihood of evolution of these benign lesions towards malignancy.

Expression of galectins in cancer: a critical review

A large body of literature has examined and described galectin expression in cancer. Discrepancies have been observed in the reported data, which hampered clear understanding of the expression profiles. This relates to the use of different types of methods that evaluate either global or specific gene expression in heterogeneous cancer tissue samples, type of antibodies used in immunohistochemistry and procedures of comparison of gene expression. In this manuscript, we review the main data concerning expression of galectins in human cancer. Only galectin-1 and galectin-3, the most abundant and examined galectins, will be examined here.

Hyalinizing Trabecular Adenoma of the Thyroid Gland

Cytologic material (fine-needle aspiration biopsy smears, thin-layer preparations, cell block sections, and touch preparations) from 29 cases of hyalinizing trabecular adenoma was studied to 1) establish the cytologic profile of the neoplasm and 2) compare the profile with those of papillary and medullary carcinoma. Papanicolaou- and Diff-Quik-stained smears of the hyalinizing trabecular adenomas were uniformly bloody. The smears featured cells in cohesive aggregates radially oriented around hyaline material, less frequently, singly. Cytoplasm was abundant, and the nucleocytoplasmic ratio was low. Intranuclear cytoplasmic inclusions, nuclear grooves, and nuclear overlapping were very common and best seen with the Papanicolaou method. Diff-Quik-stained smears highlighted the hyaline material (metachromatic), perinucleolar clearing, and cytoplasmic bodies. The combination of a bloody background, radially oriented cohesive cells, cells with abundant cytoplasm, nuclei with very frequent cytoplasmic inclusions and grooves, and the presence of hyalin should suggest the presence of hyalinizing trabecular adenoma.

Expression of galectins in cancer: A critical review

A large body of literature has examined and described galectin expression in cancer. Discrepancies have been observed in the reported data, which hampered clear understanding of the expression profiles. This relates to the use of different types of methods that evaluate either global or specific gene expression in heterogeneous cancer tissue samples, type of antibodies used in immunohistochemistry and procedures of comparison of gene expression. In this manuscript, we review the main data concerning expression of galectins in human cancer. Only galectin-1 and galectin-3, the most abundant and examined galectins, will be examined here.