Oncocytes, oxyphils, Hürthle, and Askanazy cells: morphological and molecular features of oncocytic thyroid nodules

Molecular Pathology of Thyroid Tumors: Old Problems and New Concepts

The molecular signatures of many thyroid tumors have been uncovered. These discoveries have translated into clinical practice and are changing diagnostic and tumor classification paradigms. Here, the findings of recent studies are presented with special emphasis on how molecular insights are impacting the understating of RAS mutant thyroid nodules, Hürthel cell neoplasms, and unusual thyroid tumors, such as hyalinizing trabecular tumor, secretory carcinoma of the thyroid, and sclerosing mucoepidermoid carcinoma with eosinophilia. In addition, the utility of detecting actionable molecular alterations by immunohistochemistry in advanced and aggressive thyroid cancer is also discussed.

"Copy number alteration" as the sole molecular finding of a Thyroseq test is more commonly seen in Hurthle cell neoplasms

BACKGROUND

To better understand the molecular alterations associated with Hurthle cell lesions of the thyroid, we retrospectively reviewed the association of clonal DNA copy number alterations (CNAs) with fine needle aspiration (FNA) cytomorphology and surgical follow-up.

METHODS

Hurthle cell type (HCT) and non-Hurthle cell type (NHCT) thyroid FNAs that were classified according to the Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) as atypia of undetermined significance (AUS) and suspicious for a follicular neoplasm (SFN) with corresponding molecular testing performed by ThyroSeq v3 genomic classifier were compared to surgical follow-up.

RESULTS

A total of 54 thyroid FNA cases were identified, distributed among the following categories: AUS-HCT (n = 15, 27.8%), SFN-HCT (n = 11, 20.4%), AUS-NHCT (n = 19, 35.2%), and SFN-NHCT (n = 9, 16.6%). The lesions classified as AUS-HCT and SFN-HCT showed a higher prevalence of CNAs (n = 10/26; 38.5%) compared to their NHCT counterparts (n = 3/28; 10.7%) (p < .03). Of the 42 patients (77.8%) with surgical follow-up, CNAs were more often seen in benign (n = 10/26, 38.5%) than malignant conditions (n = 1/16, 6.3%) (p < .03). CNAs were encountered in more lesions with Hurthle cell features on histologic examination (n = 8/14, 57.1%) than those without (n = 3/28, 10.7%) (p < .002). The presence of CNAs alone was seen only in benign adenomas and more commonly with Hurthle cell features (n = 5/7, 71.4%).

CONCLUSION

In this study, CNAs were associated with Hurthle cell morphology on thyroid FNA and benign adenomas upon surgical follow-up. Therefore, if the only finding of a positive ThyroSeq v3 GC result is a CNA, conservative management can be considered if clinically indicated.

Overview of the 2022 WHO Classification of Thyroid Neoplasms

This review summarizes the changes in the 5th edition of the WHO Classification of Endocrine and Neuroendocrine Tumors that relate to the thyroid gland. The new classification has divided thyroid tumors into several new categories that allow for a clearer understanding of the cell of origin, pathologic features (cytopathology and histopathology), molecular classification, and biological behavior. Follicular cell-derived tumors constitute the majority of thyroid neoplasms. In this new classification, they are divided into benign, low-risk, and malignant neoplasms. Benign tumors include not only follicular adenoma but also variants of adenoma that are of diagnostic and clinical significance, including the ones with papillary architecture, which are often hyperfunctional and oncocytic adenomas. For the first time, there is a detailed account of the multifocal hyperplastic/neoplastic lesions that commonly occur in the clinical setting of multinodular goiter; the term thyroid follicular nodular disease (FND) achieved consensus as the best to describe this enigmatic entity. Low-risk follicular cell-derived neoplasms include non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP), thyroid tumors of uncertain malignant potential, and hyalinizing trabecular tumor. Malignant follicular cell-derived neoplasms are stratified based on molecular profiles and aggressiveness. Papillary thyroid carcinomas (PTCs), with many morphological subtypes, represent the BRAF-like malignancies, whereas invasive encapsulated follicular variant PTC and follicular thyroid carcinoma represent the RAS-like malignancies. This new classification requires detailed subtyping of papillary microcarcinomas similar to their counterparts that exceed 1.0 cm and recommends not designating them as a subtype of PTC. The criteria of the tall cell subtype of PTC have been revisited. Cribriform-morular thyroid carcinoma is no longer classified as a subtype of PTC. The term "Hürthle cell" is discouraged, since it is a misnomer. Oncocytic carcinoma is discussed as a distinct entity with the clear recognition that it refers to oncocytic follicular cell-derived neoplasms (composed of > 75% oncocytic cells) that lack characteristic nuclear features of PTC (those would be oncocytic PTCs) and high-grade features (necrosis and ≥ 5 mitoses per 2 mm²). High-grade follicular cell-derived malignancies now include both the traditional poorly differentiated carcinoma as well as high-grade differentiated thyroid carcinomas, since both are characterized by increased mitotic activity and tumor necrosis without anaplastic histology and clinically behave in a similar manner. Anaplastic thyroid carcinoma remains the most undifferentiated form; squamous cell carcinoma of the thyroid is now considered as a subtype of anaplastic carcinoma. Medullary thyroid carcinomas derived from thyroid C cells retain their distinct section, and there is a separate section for mixed tumors composed of both C cells and any follicular cell-derived malignancy. A grading system for medullary thyroid carcinomas is also introduced based on mitotic count, tumor necrosis, and Ki67 labeling index. A number of unusual neoplasms that occur in the thyroid have been placed into new sections based on their cytogenesis. Mucoepidermoid carcinoma and secretory carcinoma of the salivary gland type are now included in one section classified as "salivary gland-type carcinomas of the thyroid." Thymomas, thymic carcinomas and spindle epithelial tumor with thymus-like elements are classified as "thymic tumors within the thyroid." There remain several tumors whose cell lineage is unclear, and they are listed as such; these include sclerosing mucoepidermoid carcinoma with eosinophilia and cribriform-morular thyroid carcinoma. Another important addition is thyroblastoma, an unusual embryonal tumor associated with DICER1 mutations. As in all the WHO books in the 5th edition, mesenchymal and stromal tumors, hematolymphoid neoplasms, germ cell tumors, and metastatic malignancies are discussed separately. The current classification also emphasizes the value of biomarkers that may aid diagnosis and provide prognostic information.

Recurrent Oncocytoma of the Lacrimal Sac

Oncocytoma of the lacrimal sac is an extremely rare tumor. In this report, we present the case of an 82-year-old woman who presented with swelling in the region of the lacrimal sac. Systemic examination and ophthalmic examination of both eyes were unremarkable. Computed tomography of the brain and orbits revealed a mass lesion involving the right lacrimal sac with expansion of the related nasolacrimal duct. Neither bone destruction nor tissue invasion was observed. Right external dacryocystectomy and debulking of the tumor were performed. Histopathological examination of the surgical specimen showed oncocytic cells arranged in an adenomatous fashion, and a diagnosis of benign oncocytoma was made. Three years later, the same patient presented with a similar complaint that was pathologically proven to be a recurrent benign oncocytoma of the lacrimal sac.

Unusual Case of a Caruncular Oncocytoma

ABSTRACT

Oncocytomas are benign neoplasms that are most often found in the salivary glands and kidneys. Ocular oncocytoma typically present as an asymptomatic dark blue papule on the lacrimal caruncle. Histologically, the tumor is composed of oncocytes, cells notable for eosinophilic cytoplasmic granules representing large quantities of dysfunctional mitochondria. The neoplastic proliferation may be partially or totally encapsulated and may be surrounded by myoepithelial cells. Discussed is the pathophysiology and histopathology of an ocular oncocytoma from the right lacrimal caruncle of a 68-year-old man. The patient complained of a foreign body sensation and tearing associated with a purpuric 1 × 1-mm papule of the right caruncle that had been present for 6 months. An excisional biopsy showed an oxyntic neoplasm with small cystic glandular spaces associated with goblet cells and mucin, confirmed by mucicarmine stain. Given the rarity of ocular oncocytomas and presence of mucin, exclusion of an endocrine mucin-producing sweat gland carcinoma was necessary. Peripheral myoepithelial cells noted on p63 immunostaining are seen in both endocrine mucin-producing sweat gland carcinoma and oncocytomas. However, endocrine mucin-producing sweat gland carcinoma is excluded by the presence of goblet cells, the uniform oxyphilic cytoplasm of the epithelial cells, and the negative immunohistochemical staining for neuron-specific enolase, chromogranin, synaptophysin, estrogen receptor, and progesterone receptor. Complete surgical excision is the treatment of choice for oncocytomas. This case highlights the clinical and histopathological presentation of ocular oncocytomas and raises awareness of this rare entity for both the practicing dermatologist and dermatopathologist.

Clinicopathological Characteristics and Disease-Free Survival in Patients with Hürthle Cell Carcinoma: A Multicenter Cohort Study in South Korea

BACKGROUND

Hürthle cell carcinoma (HCC), a type of thyroid carcinoma, is rare in South Korea, and few studies have investigated its prognosis.

METHODS

This long-term multicenter retrospective cohort study evaluated the clinicopathological features and clinical outcomes in patients with HCC who underwent thyroid surgery between 1996 and 2009.

RESULTS

The mean age of the 97 patients included in the study was 50.3 years, and 26.8% were male. The mean size of the primary tumor was 3.2±1.8 cm, and three (3.1%) patients had distant metastasis at initial diagnosis. Ultrasonographic findings were available for 73 patients; the number of nodules with low-, intermediate-, and high suspicion was 28 (38.4%), 27 (37.0%), and 18 (24.7%), respectively, based on the Korean-Thyroid Imaging Reporting and Data System. Preoperatively, follicular neoplasm (FN) or suspicion for FN accounted for 65.2% of the cases according to the Bethesda category, and 13% had malignancy or suspicious for malignancy. During a median follow-up of 8.5 years, eight (8.2%) patients had persistent/recurrent disease, and none died of HCC. Older age, gross extrathyroidal extension (ETE), and widely invasive types of tumors were significantly associated with distant metastasis (all P<0.01). Gross ETE (hazard ratio [HR], 27.7; 95% confidence interval [CI], 2.2 to 346.4; P=0.01) and widely invasive classification (HR, 6.5; 95% CI, 1.1 to 39.4; P=0.04) were independent risk factors for poor disease-free survival (DFS).

CONCLUSION

The long-term prognosis of HCC is relatively favorable in South Korea from this study, although this is not a nation-wide data, and gross ETE and widely invasive cancer are significant prognostic factors for DFS. The diagnosis of HCC by ultrasonography and cytopathology remains challenging.

Clinicopathological variables that correlate with sestamibi positivity in uniglandular parathyroid disease: a retrospective analysis of 378 parathyroid adenomas

PURPOSE

Technetium-99 m sestamibi parathyroid scintigraphy (MIBI scan) has been used to localize abnormal glands in patients with primary hyperparathyroidism to guide parathyroidectomy. This series aimed to identify the biochemical and histopathological correlates of MIBI scan findings in patients with parathyroid adenoma.

METHODS

A total of 378 patients with histologically and biochemically proven parathyroid adenoma were included. The results of MIBI scan, histopathological (gland volume and weight, oxyphil cell ratio), biochemical (blood and 24 h urine calcium, creatinine, glomerular filtration rate, parathormone, alkaline phosphate, and vitamin D3) variables were recorded. A positive uptake on the MIBI scan referred to a localized adenoma. Among histological variables, a cutoff of 30% was applied to define parathyroid adenomas with low (≤ 30%) and high (> 30%) oxyphil cell content. Statistical analyses were performed to assess the relationship among variables.

RESULTS

MIBI scan localized the adenoma in 306 patients. Parathyroid gland volume and weight, and oxyphil ratio were significantly higher in the MIBI scan-positive group. Among the biochemical variables, only PTH was found to be significantly increased in the MIBI scan-positive group. Binary logistic regression models identified statistically significant cutoffs for the gland volume (1700 mm³), gland weight (1.3 g) and PTH levels (170 pg/mL) that can be used to predict the MIBI scan positivity.

CONCLUSION

In addition to PTH levels, this series underscored the impact of cellular composition along with the parathyroid gland volume and weight, both of which correlate with sestamibi positivity in patients with benign uniglandular parathyroid disease.

Molecular Pathology of Thyroid Tumors: Old Problems and New Concepts

The molecular signatures of many thyroid tumors have been uncovered. These discoveries have translated into clinical practice and are changing diagnostic and tumor classification paradigms. Here, the findings of recent studies are presented with special emphasis on how molecular insights are impacting the understating of RAS mutant thyroid nodules, Hürthel cell neoplasms, and unusual thyroid tumors, such as hyalinizing trabecular tumor, secretory carcinoma of the thyroid, and sclerosing mucoepidermoid carcinoma with eosinophilia. In addition, the utility of detecting actionable molecular alterations by immunohistochemistry in advanced and aggressive thyroid cancer is also discussed.

Follicular Epithelial Dysplasia as Hashimoto Thyroiditis-Related Atypia: a Series of 91 Specimens

Follicular epithelial dysplasia (FED) is described as Hashimoto thyroiditis-related atypia and is thought to be a possible precancerous lesion. Dysplasia as an interface between normal state and carcinoma is described in a wide range of diseases and carcinogenesis chains. On the other hand, inflammation-related atypia and cancerogenesis is also widely studied. In this study, we retrospectively analyzed 91 specimens of thyroid gland surgical resections with FED during a 10-year-period at the university hospital pathology department. The study population consisted of 68 females and 15 males aged between 22 and 86 years. The preoperative cytology diagnoses had mainly been in the indeterminate categories with prevailing AUS/FLUS results in the FED-only group (p = 0.005) and suspicious for malignancy and malignant in the group with FED plus adjacent malignancy. The decision for surgery was malignancy related in 48.2% of the cases. The lesions were sized 0.1-3.5 mm and multifocal in 45.1% of the cases. Immunohistochemically, the atypical cells were cyclin D1-positive in 67.5%, galectin-3 in 72.7%, CK19 in 85.7%, and HBME-1 in 87.0% of cases. In conclusion, FED is suggested to be a pathogenetic link between inflammation-related atypia and papillary carcinoma and thus a premalignant precursor of papillary carcinoma in HT as 36.1% of the specimens contained also papillary carcinoma in the present study. Both histopathological nuclear features and the immunoprofile of FED are widely shared with that of papillary carcinoma.

Oncocytic Change in Thyroid Pathology

Oncocytes are cells that have abundant eosinophilic cytoplasm due to the accumulation of mitochondria; they are also known as oxyphils. In the thyroid they have been called Hürthle cells but this is a misnomer, since Hürthle described C cells; for this reason, we propose the use of "oncocyte" as a scientific term rather than an incorrect eponym. Oncocytic change occurs in nontumorous thyroid disorders, in benign and malignant tumors of thyroid follicular cells, in tumors composed of thyroid C cells, and intrathyroidal parathyroid proliferations as well as in metastatic lesions. The morphology of primary oncocytic thyroid tumors is similar to that of their non-oncocytic counterparts but also is complicated by the cytologic features of these cells that include both abundant eosinophilic cytoplasm and large cherry red nucleoli. The molecular alterations in oncocytic thyroid tumors echo those of their non-oncocytic counterparts but in addition feature mitochondrial DNA mutations as well as chromosomal gains and losses. In this review we emphasize the importance of recognition of the spectrum of oncocytic thyroid pathology. The cell of origin, morphologic features including architecture, nuclear atypia and invasive growth, as well as high grade features such as mitoses and necrosis, enable accurate classification of these lesions. The molecular alterations underlying the pathological entity are associated with genetic alterations associated with oncocytic change. The arbitrary cut-off of 75% oncocytic change to classify a lesion as an oncocytic variant brings another complexity to the classification scheme of tumors that frequently have mixed oncocytic and non-oncocytic components. This controversial and often confusing area of thyroid pathology requires thoughtful and cautious investigation to clarify accurate diagnosis, prognosis and prediction for patients with oncocytic thyroid lesions.

Challenges in Cytology Specimens With Hürthle Cells

In fine-needle aspirations (FNA) of thyroid, Hürthle cells can be found in a broad spectrum of lesions, ranging from non-neoplastic conditions to aggressive malignant tumors. Recognize them morphologically, frequently represents a challenging for an adequately diagnosis and are associated with a significant interobserver variability. Although the limitations of the morphologic diagnosis still exist, the interpretation of the context where the cells appear and the recent advances in the molecular knowledge of Hürthle cells tumors are contributing for a more precise diagnosis. This review aims to describe the cytology aspects of all Hürthle cells neoplastic and non-neoplastic thyroid lesions, focusing on the differential diagnosis and reporting according to The Bethesda System for Reporting Thyroid Cytology (TBSRTC). New entities according to the latest World Health Organization (WHO) classification are included, as well as an update of the current molecular data.

Oncocytic Papillary Thyroid Carcinoma and Oncocytic Poorly Differentiated Thyroid Carcinoma: Clinical Features, Uptake, and Response to Radioactive Iodine Therapy, and Outcome

OBJECTIVE

The main objective of this study was to review the clinicopathologic characteristics and outcome of patients with oncocytic papillary thyroid carcinoma (PTC) and oncocytic poorly differentiated thyroid carcinoma (PDTC). The secondary objective was to evaluate the prevalence and outcomes of RAI use in this population.

METHODS

Patients with oncocytic PTC and PDTC who were treated at a quaternary cancer centre between 2002 and 2017 were retrospectively identified from an institutional database. All patients had an expert pathology review to ensure consistent reporting and definition. The cumulative incidence function was used to analyse locoregional failure (LRF) and distant metastasis (DM) rates. Univariable analysis (UVA) was used to assess clinical predictors of outcome.

RESULTS

In total, 263 patients were included (PTC [n=218], PDTC [n=45]) with a median follow up of 4.4 years (range: 0 = 26.7 years). Patients with oncocytic PTC had a 5/10-year incidence of LRF and DM, respectively, of 2.7%/5.6% and 3.4%/4.5%. On UVA, there was an increased risk of DM in PTC tumors with widely invasive growth (HR 17.1; p<0.001), extra-thyroidal extension (HR 24.95; p<0.001), angioinvasion (HR 32.58; p=0.002), focal dedifferentiation (HR 19.57, p<0.001), and focal hobnail cell change (HR 8.67, p=0.042). There was additionally an increased risk of DM seen in male PTC patients (HR 5.5, p=0.03).The use of RAI was more common in patients with larger tumors, angioinvasion, and widely invasive disease. RAI was also used in the management of DM and 43% of patients with oncocytic PTC had RAI-avid metastatic disease. Patients with oncocytic PDTC had a higher rate of 5/10-year incidence of LRF and DM (21.4%/45.4%; 11.4%/40.4%, respectively). Patients with extra-thyroidal extension had an increased risk of DM (HR 5.52, p=0.023) as did those with angioinvasion. Of the patients with oncocytic PDTC who received RAI for the treatment of DM, 40% had RAI-avid disease.

CONCLUSION

We present a large homogenous cohort of patients with oncocytic PTC and PDTC, with consistent pathologic reporting and definition. Patients with oncocytic PTC have excellent clinical outcomes and similar risk factors for recurrence as their non-oncocytic counterparts (angioinvasion, large tumor size, extra-thyroidal extension, and focal dedifferentiation). Compared with oncocytic PTCs, the adverse biology of oncocytic PDTCs is supported with increased frequency of DM and lower uptake of RAI.

Hürthle cell lesions of the thyroid: Progress made and challenges remaining

Hürthle cell-predominant thyroid fine needle aspirations (FNA) are encountered frequently in routine practice, yet they are often challenging to diagnose accurately and are associated with significant interobserver variability. This is largely due to the ubiquity of Hürthle cells in thyroid pathology, ranging from nonneoplastic conditions to aggressive malignancies. Although limitations in cytomorphologic diagnoses likely will remain for the foreseeable future, our knowledge of the molecular pathogenesis of Hürthle cell neoplasia and application of molecular testing to cytologic material have increased dramatically within the past decade. This review provides context behind the challenges in diagnosis of Hürthle cell lesions and summarizes the more recent advances in diagnostic tools.

Hürthle-cell neoplasms of the thyroid: An algorithmic approach to pathologic diagnosis in light of molecular advances

Our understanding of neoplasia is evolving at a rapid pace in these exciting times, where recent molecular pathology advances are reinforcing and fine tuning morphological divisions and classification. Thyroid gland neoplasia in general, and Hürthle-cell neoplasms in particular, are no exception in the current era of histopathology-molecular biology paradigm. In this review paper, we discuss the rationale that led pathologists in the past to separate Hürthle-cell neoplasms into its own dedicated diagnostic category, and provide an algorithmic approach to the differential diagnosis of oncocytic lesions of the thyroid. This review will also shed light on the current WHO classification of Hürthle-cell neoplasms in light of molecular advances that justify histopathologic distinctions.

The Presence of Hürthle Cells Does Not Increase the Risk of Malignancy in Most Bethesda Categories in Thyroid Fine-Needle Aspirates

Background: Hürthle cell/oncocytic change is commonly reported on thyroid fine-needle aspiration (FNA) and may be considered an "atypical cell" by clinicians. This study aims to delineate the association between Hürthle cells in preoperative cytology and subsequent pathology of the indexed thyroid nodule and to report rates of malignancy. Methods: Retrospective review of records of 300 patients with Hürthle cell/oncocytic change on FNA and final surgical pathology at a tertiary referral center between 2000 and 2013 was performed and compared with a multi-institutional FNA cohort. The degree of Hürthle cell presence was correlated with histopathologic diagnoses. Results: In the Hürthle cell FNA group, Bethesda System for Reporting Thyroid Cytopathology (BSRTC) categories were as follows: I (nondiagnostic) 14 (4.7%); II (benign) 113 (37.7%); III (atypia of undetermined significance/follicular lesion of undetermined significance) 33 (11%); IV (follicular neoplasm/suspicious for a follicular neoplasm) 125 (41.6%); V (suspicious for malignancy) 12 (4%); and VI (malignant) 3 (1%). When categorized based on the degree of Hürthle cell change, 59 (29%) were classified as mild, 13 (6%) moderate, and 131 (65%) as predominant. When comparing the results with a multi-institutional FNA cohort (all with surgical confirmation), the presence of Hürthle cells was found to be associated with a lower risk of malignancy in all BSRTC categories, with a statistically significant difference in the BSRTC IV and V groups. The sole exception was when Hürthle cell presence was classified as predominant (defined as >75% of the cellular population); the rate of malignancy was significantly elevated in FNAs interpreted as benign/Bethesda II. Conclusions: Although Hürthle cells have been considered by clinicians as an "atypical cell," their presence does not increase the risk of malignancy within BSRTC categories overall. However, when predominant Hürthle cell change is present, the risk of malignancy is increased in the benign cytology/BSRTC category II.

Clinicopathological features and outcomes after radioactive iodine treatment of oncocytic well-differentiated thyroid carcinomas

OBJECTIVE

The aim of this study was to compare the clinicopathological features of Hürthle cell carcinomas (HCC) and oncocytic papillary thyroid carcinomas (OPTC) and to evaluate their response to radioactive iodine (RAI) treatment.

METHODS

We retrospectively reviewed the charts of patients with histopathologically verified OPTC (group 1) and HCC (group 2), during a 17-year period. All patients underwent total thyroidectomy and received RAI adjuvant therapy. Clinicopathological characteristics of the two groups were compared. Response to initial therapy was assessed 6 to 24 months after RAI ablation according to the American Thyroid Association dynamic risk reclassification. Clinical outcomes were evaluated.

RESULTS

A total of 28 patients (8 OPTC and 20 HCC) were included. There was no significant difference in clinicopathological features including sex, age, tumour size and vascular invasion. Distant metastases were absent in both groups. OPTC, however, presented more features of local invasion (50% vs. 10%, P = 0.03), extrathyroidal extension (25% vs. 0%, P = 0.07) and lymph node involvement (37.5% vs. 0%, P = 0.01). Median cumulative RAI activity administered to both groups was 200 mCi (range: 100-300 mCi). Response to RAI therapy was excellent in all HCC and 87.5% of OPTC (P = 0.28). One patient with OPTC (12.5%) presented an indeterminate response. Clinical outcomes were favourable after a median follow-up of 87.5 and 49 months, respectively.

CONCLUSION

Although OPTC presented more locoregional invasion, clinicopathological characteristics of OPTC and HCC were comparable. Both OPTC and HCC were iodine responsive. We suggest that adjuvant RAI therapy after total thyroidectomy is beneficial for OPTC and HCC and may improve disease-free survival.

Malignancy risk for solitary and multiple nodules in Hürthle cell-predominant thyroid fine-needle aspirations: A multi-institutional study

BACKGROUND

Hürthle cell metaplasia is common in hyperplastic nodules, particularly within the setting of lymphocytic thyroiditis (LT). The Bethesda System for Reporting Thyroid Cytopathology indicates that it is acceptable to classify Hürthle cell-predominant fine-needle aspiration (HC FNA) specimens as atypia of undetermined significance (AUS) rather than suspicious for a Hürthle cell neoplasm (HUR) within the setting of multiple nodules or known LT. The goal of the current study was to address whether this approach is justified.

METHODS

HC FNA specimens were identified and correlated with ultrasound and surgical pathology reports if available. Multinodularity was determined based on findings on macroscopic examination if imaging results were unavailable.

RESULTS

A total of 698 HC FNA specimens were identified, including 576 resected nodules, 455 of which (79%) were benign. The overall risk of malignancy for HUR was 27%, whereas the risk of malignancy for AUS was 10%. The mean size of the benign nodules was 2.1 cm on surgical resection specimens, with multiple nodules noted in 293 cases (64%) and histologic LT noted in 116 cases (25%). The mean size of the malignant nodules was 2.8 cm, with multiple nodules and histologic LT noted in 74 cases (61%) and 22 cases (18%), respectively. The malignancy rate did not differ between solitary or multiple nodules (P = .52) or in the presence or absence of LT (P = .12). However, size did significantly differ between malignant and benign nodules (P < 0.01).

CONCLUSIONS

The malignancy rate did not differ significantly in the presence of multiple nodules or LT, although the latter demonstrated a statistical trend. A diagnosis of AUS over HUR based solely on the presence of multinodularity is not warranted.

Hürthle cell lesions on thyroid fine needle aspiration cytology: Molecular and histologic correlation

BACKGROUND

Hürthle cell lesions often pose diagnostic challenges, despite their common occurrence on thyroid fine-needle aspiration cytology (FNAC). The associated molecular alterations are also not well understood. Therefore, our study aimed to delineate the molecular profile of Hürthle cell lesions classified as Bethesda Categories III or IV (atypia of undetermined significance (AUS) or suspicious for follicular neoplasm (SFN)) on FNAC and to correlate this molecular profile with surgical resection findings.

METHODS

This study consisted of 188 Hürthle cell lesions with indeterminate cytology and ThyroSeq® v2/v3 molecular testing results. Surgical follow-up was available for 33 cases.

RESULTS

The majority of indeterminate Hürthle cell lesions had negative ThyroSeq® results (61%) and were benign on available surgical follow-up. The most prevalent mutations involved the RAS gene (21%), which were associated with benign lesions, non-invasive follicular thyroid neoplasms with papillary-like nuclear features (NIFTP), and malignancy. The remaining mutations involved less than 18% of the cases, including PAX8/PPARG (3.7%), TSHR (3.7%), EIF1AX (2.7%), MET (2.1%), PTEN (1.6%), clonal copy number alteration (1.6%), TERT (1.1%), and 0.5% each of GNAS, PIK3CA, and TP53 mutations. On follow-up, 45% were benign, 24% were NIFTP, and 30% were malignant. The malignant cases had different molecular alterations.

CONCLUSION

No single molecular alteration defines cytologically indeterminate Hürthle cell lesions; the majority of cases have low-risk or no molecular alterations and are benign on follow-up. These findings suggest that molecular testing may be useful, but is not definitive, in determining which cases may be managed conservatively; additional studies are needed to fully determine the negative predictive value in ruling out malignancy.

Diagnostic performance of thyroid ultrasound in Hürthle cell carcinomas

OBJECTIVE

Hürthle cell carcinomas (HCCs) of the thyroid have been recently reclassified as a separate entity due to their distinct clinical and molecular profiles. Few studies have assessed the ability of preoperative characteristics in differentiating HCCs from Hürthle cell adenomas (HCAs) due to the low prevalence of both lesions. This study aimed to compare the preoperative features of HCCs and HCAs and evaluate the diagnostic performance of ultrasound in distinguishing between both.

SUBJETCS AND METHODS

Retrospective study including 101 patients (52 HCCs and 49 HCAs) who underwent thyroid surgery from 2000 to 2016. Clinical, ultrasonographic, and histological data were reviewed. Diagnostic performance of suspicious sonographic features was analyzed in 51 cases (24 HCCs and 27 HCAs).

RESULTS

Hürthle cell neoplasms were predominant in females. Subjects ≥ 55 years represented 58% of the cases of HCCs and 53% of those of HCAs. Carcinomas were significantly larger (p < 0.001), and a tumor size ≥ 4 cm significantly increased the risk of malignancy (odds ratio 3.67). Other clinical, cytologic, and sonographic data were similar between HCCs and HCAs. Among the HCCs, the lesions were purely solid in 54.2%, hypoechoic in 37.5%, and had coarse calcifications in 12.5%, microcalcifications in 8.3%, irregular contours in 4.2%, and a taller-than-wide shape in 16.7%. Predominantly/exclusive intranodular vascularization was observed in 52.6%. Overall, 58% of the HCCs were classified as TI-RADS 4 or 5 compared with 48% of the HCAs. TI-RADS 4 or 5 had a specificity of only 51.8% and a positive likelihood ratio of 1.21.

CONCLUSIONS

Apart from the lesion size, no other preoperative feature adequately distinguished HCCs from HCAs. Sonographic characteristics raising suspicion for malignancy, which are mostly present in papillary carcinomas, were infrequent in HCCs. New tools must be developed to improve preoperative diagnosis and deferral of surgery in cases of adenomas.

The Current Histologic Classification of Thyroid Cancer

Thyroid cancers of follicular cell derivation provide excellent phenotype-genotype correlations. Current morphologic classifications are complex and require simplification. Benign adenomas have follicular or papillary architecture and bland cytology. Well-differentiated thyroid carcinomas exhibit follicular architecture, expansile growth, and variable cytologic atypia and invasiveness; low-risk tumors have excellent prognosis after surgical resection whereas widely-invasive and angioinvasive tumors warrant total thyroidectomy and radioablation. Papillary carcinoma is less differentiated; indolent microcarcinomas can be managed by active surveillance, whereas clinical lesions with local or distant spread require therapy. Progression gives rise to poorly differentiated and anaplastic carcinomas that are less common but far more aggressive.

Hürthle cell metaplasia in chronic lymphocytic thyroiditis: Role of age factor and review of literature on its molecular pathogenesis

OBJECTIVES

Hürthle cell (HC) metaplasia is an important feature of chronic lymphocytic (Hashimoto) thyroiditis (HT). However, it is rarely observed in juvenile form HT. In a study based on fine needle aspiration cytology, the cytomorphological difference between pediatric HT and its adult form was studied, with special attention on HC metaplasia and its pathogenesis.

MATERIALS AND METHODS

The frequency of following 12 cytomorphological features in 16 pediatric and 104 adult HT cases were compared: follicular cells, lymphoid cells, HCs, plasma cells, lympho-histiocytic aggregates, epithelioid histiocytes, multinucleated giant cells, fire-flare appearance, colloid, intracytoplasmic lumen (ICL) with or without colloid inclusion, paravacuolar granules, and cyst cells. The age decade distribution of HC metaplasia was analyzed.

RESULTS

Significant difference was observed between pediatric HT and its adult form in respect of HC metaplasia and ICL with colloid inclusion in HC. HC were present in 7 (43.8%) of pediatric and 94 (90.4%) of adult HT cases (P = 0.00006). 1 (6.3%) pediatric and 35 (33.7%) adult HT cases had ICL with colloid inclusion in HC (P = 0.03698). As compared to first two decades of life, significantly higher number of cases revealed HC metaplasia in every decade from third decade onwards (P = 0.01290-0.00009); however, the difference in respect of ICL with colloid inclusions attained significance during sixth decade only (P = 0.00235).

CONCLUSIONS

Hürthlization, which appears to be survival response, is rare in pediatric HT and becomes more pronounced starting from third decade onwards; significant increase in ICL with colloid inclusion is a much more delayed phenomenon.

Patients with Oncocytic Variant Papillary Thyroid Carcinoma Have a Similar Prognosis to Matched Classical Papillary Thyroid Carcinoma Controls

BACKGROUND

Previous studies have suggested that oncocytic variant papillary thyroid carcinoma (PTC) may be more aggressive, with higher rates of recurrent disease. The aim of this study was to evaluate characteristics and outcomes of patients with oncocytic variant PTC compared to classical PTC.

METHODS

Patients with oncocytic variant PTC were retrospectively identified from 519 patients who underwent thyroidectomy for PTC between January 2009 and August 2015. Data collected included patient demographics, laboratory and pathology findings, imaging studies, treatment, and follow-up. Patients were matched 1:1 by age, sex, and TNM stage with patients who underwent total thyroidectomy for classical PTC during the same time period.

RESULTS

The cohort included 21 patients, of whom 18 (86%) were female, with a median age of 53 years (range 23-68 years). All patients underwent total thyroidectomy, and 17 (81%) had a central compartment neck dissection (8 [38%] prophylactic). The median tumor size was 2.0 cm (range 0.9-6.5 cm), and four (19%) patients had extrathyroidal extension. There was no significant difference in histopathologic characteristics, including extrathyroidal extension and lymphovascular invasion, between the two groups except for an increased incidence of thyroiditis in oncocytic variant PTC (90.5% vs. 57%; p = 0.01). In oncocytic variant PTC patients who underwent central compartment neck dissection, malignant lymph nodes were found in 12 (57%) patients compared to 13 (62%) classical (p = 0.75). Lateral neck dissection was performed in 5 (24%) oncocytic variant and classical PTC patients, with metastatic lymphadenopathy found in four (a median of four malignant lymph nodes; range 1-6) and five (a median of 2.5 malignant lymph nodes; range 1-9), respectively. Radioactive iodine was administered to 18 (86%) oncocytic variant PTC and 18 (86%) classical PTC patients. At a median follow-up of 51 months (interquartile range 38-61), one oncocytic variant PTC patient had recurrent disease and underwent reoperation at 24 months. In classical PTC patients with a median follow-up time of 77 months (range 56-87 months), two (9.5%) patients had detectable thyroglobulin levels indicating early recurrence, but neither has undergone reoperation.

CONCLUSIONS

Oncocytic variant PTC was present in 5% of PTC patients. Most (95%) patients remain disease-free at four years, similar to classical PTC outcomes, suggesting that oncocytic variant may not represent a more aggressive variant.

Cytologic Diagnosis of Oncocytic Neoplasms of the Thyroid Gland: The Importance of the Clinical Scenario

It is a diagnostic challenge to differentiate benign and malignant thyroid neoplasms made up of Hürthle (or oncocytic) cells on cytologic material. They are large, polygonal cells with marked eosinophilic, granular cytoplasm reflective of overly abundant mitochondria. These cells commonly occur in nodular goiters and dominant adenomatous or hyperplastic nodules though they may also be the predominant component of neoplastic lesions. There are significant controversies concerning the optimal management of patients with oncocytic cell carcinoma. This review provides an overview of the most significant studies addressing the distinction between benign and malignant Hürthle cell lesions on cytology and histology.

Synchronous and bilateral oncocytic carcinoma of the breast: A case report and review of the literature

Synchronous bilateral breast cancer is rare, and oncocytic carcinoma is an even rarer breast cancer histological subtype. In general, oncocytic tumors are defined as neoplasms with eosinophilic granular cytoplasm and have been reported in various organs. Oncocytic carcinoma of the breast was first documented by Gădăleanu and Craciun in 1987, and 48 cases have since been reported. The present study reports a case of synchronous bilateral breast oncocytic carcinoma. The patient was a 78-year-old woman. Although she exhibited no symptoms, chest computed tomography revealed three multinodular breast tumors: Two in the right breast and one in the left. Core needle biopsy was performed on the three tumors, and the patient was diagnosed with invasive ductal carcinoma with potential apocrine carcinoma. A bilateral modified radical mastectomy was performed. Surgical specimens of the three tumors revealed cord- or nest-forming tumor cells with eosinophilic granular cytoplasm. Immunohistochemically, the tumor cells were markedly positive for mitochondria. Electron microscopy of the tumor samples additionally revealed numerous mitochondria filling the cytoplasm. Based on these findings, the tumors were diagnosed as oncocytic carcinoma. The pathogenesis of oncocytic carcinoma remains to be fully elucidated; thus, additional clinicopathological studies are required.

Implications of oncocytic change in papillary thyroid cancer

OBJECTIVE

Although the presence of oncocytic change in less than 75% of a tumour is not considered to indicate oncocytic variants of papillary thyroid carcinoma (PTC), we frequently observe partial oncocytic change, especially in obese PTC patients. Thus, we sought to investigate the relationship between the presence of oncocytic change of PTC and its prognosis.

DESIGN, SETTING AND PARTICIPANTS

We retrospectively studied 142 patients with PTC who had undergone surgery between 2000 and 2005, and re-evaluated their PTC slides to record the proportion of oncocytic change in 10% increments from 0% to 100%.

MAJOR OUTCOME MEASURE

We analysed the relationship between the proportion of oncocytic change and clinicopathological prognostic factors.

RESULTS

Oncocytic change was found in 45·8% (65/142) of PTC patients. The proportion of patients with oncocytic change was higher in obese patients than in lean patients and showed a significant correlation with the BMI (r = 0·195, P = 0·020). The PTC patients with oncocytic change showed a higher recurrence rate than PTC patients without oncocytic change (30·8% vs 11·7%, respectively; P = 0·005). The presence of oncocytic change in PTC patients was associated with a shorter disease-free survival in a Kaplan-Meier analysis after a mean follow-up of 8·9 years.

CONCLUSION

The patients with PTC with oncocytic change presented with a higher recurrence rate and were more likely to be obese. These findings suggest that presence of oncocytic change is a poor prognostic factor in PTC patients, even if the oncocytic change involves less than 75% of a tumour.

Intrathyroidal oxyphilic parathyroid carcinoma: A potential diagnostic caveat in cytology?

Oxyphilic (oncocytic) parathyroid lesions are very uncommon and their cytological features are rarely described. Due to the similarities in anatomical location and indistinguishable cytomorphological features, these lesions are easily confused with neoplastic and non-neoplastic thyroid lesions on fine needle aspiration (FNA). The diagnosis becomes more challenging in cases of unusual intrathyroidal location of the parathyroid lesions in the absence of clinical evidence of hyperparathyroidism, which simulate thyroid nodules clinically. We describe a case of intrathyroidal oxyphilic parathyroid carcinoma in a 66-year-old female, who presented with a dominant left "thyroid" nodule. FNA smears were cellular, comprising predominantly of oxyphilic cells arranged in papillary-like architecture with occasional nuclear grooves, which was mistaken for oncocytic variant of papillary carcinoma of the thyroid. The histological diagnosis of oxyphilic parathyroid "adenoma" was made following total thyroidectomy. The tumor, unfortunately, recurred 7 years later with associated multiple lung metastases. When dealing with thyroid lesions comprising predominantly of oncocytic cells, one should consider oxyphilic parathyroid neoplasms as one of the differential diagnosis. In difficult equivocal cases, a panel of immunocytochemical stains (PTH, GATA3, TTF-1, PAX8, and thyroglobulin) can be helpful. In addition, a combination of valuable clinical, radiological, and laboratory data, including serum calcium and parathyroid hormone levels are key to arriving at an accurate cytological diagnosis. Diagn. Cytopathol. 2016;44:688-692. © 2016 Wiley Periodicals, Inc.

Hidradenoma Papilliferum With Oncocytic Metaplasia: A Histopathological and Immunohistochemical Study

Hidradenoma papilliferum is a benign cutaneous adnexal neoplasm, commonly occurring in the vulva and perianal region of adult women. It has characteristic histopathological features composed of anastomosing and branching tubules, lined by columnar cells, and a basal layer of myoepithelial cells. A 39-year-old woman was evaluated for 2 asymptomatic labial masses. The histopathological examination revealed a Bartholin's cyst and a hidradenoma papilliferum. The latter contains a distinct area of oncocytic/oxyphilic metaplasia. Immunohistochemical stains revealed positive staining for gross cystic disease fluid protein (GCDFP)-15 and androgen receptor. GATA-3, a protein expressed in sweat glands, highlights a similar positive staining pattern with weaker staining in areas of oncocytic metaplasia. P63 highlighted the myoepithelial differentiation. In situ hybridization for Human Papilloma Virus 6, 11, 16, and 18 was negative. P53 was negative and Ki-67 was low, confirming its benign nature. Oncocytes are enlarged epithelial cells with voluminous eosinophilic granular cytoplasm resulting from staining of nonribosomal cytoplasmic components. Few reports documented it in hidradenoma papilliferum. Our case demonstrated a florid distinct appearance of this metaplasia. The immunoprofiles of this oncocytic metaplasia such as p53 negativity and positivity for androgen receptor and GCDFP-15 demonstrates similarity to apocrine metaplasia in the breast. The authors' case demonstrates the benign nature of oncocytic metaplasia and supports the common origin of oncocytic cells and columnar cells in hidradenoma papilliferum.

Hurthle Cell Lesion: Controversies, Challenges, and Debates

Hurthle cell lesion is one of the most questionable clinico-pathological entities in most of its aspects. Literature has used the terms oncocytic, oxyphilic, Hurthle, and Ashkanazy interchangeably; what does each term denote? Who first described these cells? What is the cell of origin? How much Hurthle cells should be present to define the lesion as Hurthle cell one? Is it possible to differentiate hyperplastic from neoplastic and benign from malignant Hurthle cell lesion on a non-histopathologic ground? Does it belong to follicular or to papillary neoplasms or should it be classified separately? Can we anticipate its clinical behavior or predict its outcome? How can we manage? We will try to answer these questions in light of the ongoing relevant arguments with the aim of resolving some uncertainties and suggesting how to solve others.

Dysregulation of Parkin-mediated mitophagy in thyroid Hürthle cell tumors

Abnormal accumulation of defective mitochondria is the hallmark of oncocytes, which are frequently observed in thyroid Hürthle cell lesions. Autophagy is an essential cellular catabolic mechanism for the degradation of dysfunctional organelles and has been implicated in several human diseases. It is yet unknown how autophagic turnover of defective mitochondria in Hürthle cell tumors is regulated. We characterized the expression patterns of molecular markers including Beclin1, LC3, PINK1 and Parkin, which are required for autophagy or mitophagy, in human oncocytic lesions of the thyroid. To undertake mechanistic studies, we investigated autophagy and mitophagy using XTC.UC1 cells, the only in vitro model of Hürthle cell tumors. Beclin1 and LC3 were highly expressed in oncocytes of Hürthle cell tumors. XTC.UC1 showed autophagic responses to starvation and rapamycin treatment, whereas they displayed ineffective activation of mitophagy, which is triggered by the coordinated action of PINK1 and Parkin in response to CCCP. This resulted in a decreased turnover of abnormal mitochondria. The mechanisms underlying defective mitophagy and mitochondrial turnover were investigated by genetic analysis of the PARK2 gene in XTC.UC1 and Hürthle cell tumor tissues. XTC.UC1 and several tumors harbored the V380L mutation, resulting in dysfunctional autoubiquitination and decreased E3 ligase activity. Consistently, oncocytes in Hürthle cell tumors displayed comparable expression of PINK1 but decreased Parkin expression in comparison to normal thyrocytes. The introduction of wild-type Parkin sensitized XTC.UC1 to death induced by CCCP. This study provides a possible etiological basis for oncocytic formation in heterogeneous Hürthle cell tumors through insufficient mitophagy leading to ineffective turnover of aberrant mitochondria caused by dysfunctional Parkin-mediated pathways of mitochondria quality control.

Oncocytic lesions of the neuroendocrine system

This paper reviews the pathologic features of lesions which are oncocytic and involve classic endocrine organs. The history of the oncocytic cell, its morphologic and ultrastructural features, and important immunohistochemical findings are reviewed. Oncocytic proliferations including non-neoplastic and neoplastic of the thyroid, parathyroid, adrenal (both cortex and medulla), and pituitary are described. Their clinical relevance, functional capacity and capability, and where appropriate, prognostic implications are discussed. Important and relevant molecular biological information is included where appropriate.

Hürthle cells in fine-needle aspirates of the thyroid: a review of their diagnostic criteria and significance

Although the cytological assessment of Hürthle cell lesions is challenging, the literature offers good, albeit imperfect, guidance to aid in the crucial distinction between nonneoplastic and neoplastic lesions. The significance of a cytologic diagnosis of follicular neoplasm, Hürthle cell type, lies in the rate of malignancy on follow-up surgical excision, ranging in the literature from 10% to 45%. A cytodiagnosis of atypia of undetermined significance (AUS), Hürthle cell type, appears to be associated with a lower risk of malignancy on follow-up than other subtypes of AUS; however, this area warrants further investigation.

Hürthle cell presence alters the distribution and outcome of categories in the Bethesda system for reporting thyroid cytopathology

OBJECTIVES

We aimed to determine whether the presence of Hürthle cells altered the distribution of categories in the Bethesda system for reporting thyroid cytopathology, or the expected neoplastic and malignant outcome.

METHODS

Fine needle aspiration (FNA) cytology reports of Hürthle cells in a 2-year period were evaluated. The distribution of Bethesda system categories and the outcome at partial or complete thyroidectomy were compared for FNAs with and without Hürthle cells.

RESULTS

Of 895 adequate FNAs with Hürthle cells, 764 (85.4%) were classified as benign, 86 (9.6%) as atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS), 32 (3.6%) as follicular neoplasm/suspicious for follicular neoplasm (FN/SFN), 12 (1.3%) as suspicious for malignancy (SFM) and one (0.1%) as malignant. Of 10 359 adequate FNAs without Hürthle cells, 9707 (93.7%) were classified as benign, 412 (4.0%) as AUS/FLUS, 77 (0.7%) as FN/SFN, 93 (0.9%) as SFM and 70 (0.7%) as malignant. The distribution of categories in FNAs with and without Hürthle cells was significantly different (P < 0.001) as a result of a decrease in benign and an increase in AUS/FLUS and FN/SFN categories. Among 128 patients with and 582 without Hürthle cells undergoing surgery, the overall neoplastic and malignancy rates were higher in the former than in the latter group (27.3% versus 14.9%, P < 0.001; 21.1% versus 11.7%, P = 0.003; respectively). Although neoplastic and malignant rates were higher in the group with than without Hürthle cells in all categories, the differences were only significant for a neoplastic outcome of benign cytology (15.1% versus 6.0%, P = 0.0013) and a malignant outcome of FN/SFN cytology (63.6% versus 21.9%, P = 0.0108).

CONCLUSIONS

We found that the rates of AUS/FLUS and FN/SFN categories in the Bethesda system were higher when Hürthle cells were present. After surgery, neoplastic and malignant outcomes were significantly higher in the Hürthle cell group.

Precursor lesions of endocrine system neoplasms

The concept of precursor lesions of endocrine neoplasms is a new and interesting topic in endocrine pathology. A variety of clinicopathological conditions are associated with a sequence of cellular changes from hyperplasia to neoplasia; dysplasia is, in contrast, quite rare. The majority of precursor lesions is associated with familial genetic syndromes. These include C-cell hyperplasia in thyroid that is associated with familial medullary thyroid carcinoma, adrenal medullary hyperplasia as a precursor of phaeochromocytomas in MEN2 syndrome, rare pituitary adenohypophyseal cell hyperplasia in familial syndromes associated with pituitary adenomas, MEN1-related precursor gastric enterochromaffin-like cell (ECL) hyperplasia, and duodenal gastrin producing (G) and/or somatostatin producing (D) cell hyperplasia that give rise to type II gastric neuroendocrine tumours (NETs) and duodenal NETs, respectively, and MEN1- or VHL-related islet hyperplasia, islet dysplasia and ductulo-insular complexes that are associated with pancreatic NETs. Other hyperplasias are not thought to be associated with genetic predisposition. Some are attributed to inflammation; autoimmune chronic atrophic gastritis-related ECL hyperplasia can progress to type I gastric NETs, and EC (enterochromaffin) cell or L cell hyperplasia associated with inflammatory bowel diseases can progress to colorectal NETs. In the lung, diffuse idiopathic pulmonary neuroendocrine cell hyperplasia can give rise to peripherally-located low grade pulmonary NETs and tumourlets (neuroendocrine microtumours <5  mm). Rarely, secondary hyperplasias develop into autonomous neoplasms, as in tertiary hyperparathyroidism or pituitary thyrotroph adenomas in primary hypothyroidism. While some precursor lesions, such as thyroid C cell hyperplasia, represent frankly premalignant conditions, others may represent a sequence of proliferative changes from hyperplasia to benign neoplasia that may also progress to malignancy.

Does Hürthle cell carcinoma of the thyroid have a poorer prognosis than ordinary follicular thyroid carcinoma?

BACKGROUND

Hürthle cell carcinoma (HCC) is a rare form of thyroid carcinoma and is considered an oxyphilic variant of follicular thyroid carcinoma. However, little is known about its biological characteristics or clinical behavior. We conducted a retrospective study to determine whether the prognosis of HCC differs from that of ordinary follicular thyroid carcinoma (OFC).

METHODS

The subjects were the 558 patients with follicular thyroid carcinoma who underwent initial surgery at our institution between 1989 and 2010 and consisted of 73 patients with HCC and 485 patients with OFC. There were 410 females and 148 males, and their median age was 51 years. A univariate analysis was conducted in relation to cumulative cause-specific survival (CSS) according to the Kaplan-Meier method for the following variables: age at the time of initial surgery, gender, tumor size, invasiveness, distant metastasis at presentation, and histological type (HCC vs OFC). Differences between groups were analyzed for significance by the log-rank test. Multivariate analysis was performed by using the Cox proportional hazard model.

RESULTS

A total of 4 patients (5.5%) in the HCC group had distant metastasis compared with 106 patients (21.9%) in the OFC group. Significant factors in relation to CSS in the univariate analyses were age, tumor size, and invasiveness, but there were no significant differences between the HCC group and the OFC group. Multivariate analysis showed that age, tumor size, and distant metastasis at presentation were significant factors.

CONCLUSIONS

HCC does not have a poorer prognosis than OFC.

Hashimoto's thyroiditis: celebrating the centennial through the lens of the Johns Hopkins hospital surgical pathology records

Hashimoto's thyroiditis is now considered the most prevalent autoimmune disease, as well as the most common endocrine disorder. It was initially described in 1912, but only rarely reported until the early 1950s. To celebrate this centennial, we reviewed the surgical pathology archives of the Johns Hopkins hospital for cases of Hashimoto's thyroiditis, spanning the period from May 1889 to October 2012. Approximately 15,000 thyroidectomies were performed at this hospital over 124 years. The first surgical case was reported in 1942, 30 years after the original description. Then, 867 cases of Hashimoto's thyroiditis were seen from 1942 to 2012, representing 6% of all thyroidectomies. Hashimoto's thyroiditis was the sole pathological finding in 462 cases; it accompanied other thyroid pathologies in the remaining 405 cases. The most commonly associated pathology was papillary thyroid cancer, an association that increased significantly during the last two decades. The most common indication for thyroidectomy was a thyroid nodule that was cytologically suspicious for malignancy. Hashimoto's thyroiditis remains a widespread, intriguing, and multifaceted disease of unknown etiology one century after its description. Advances in the understanding of its pathogenesis and preoperative diagnosis will improve recognition and treatment of this disorder, and may one day lead to its prevention.

Villous papillary thyroid carcinoma: a variant associated with marfan syndrome

Marfan syndrome (MFS) is an autosomal dominant hereditary disorder of connective tissue associated with perturbations in transforming growth factor β (TGF-β) biology, most often due to mutations in FBN1 gene that encodes fibrillin-1. To our knowledge, there is no known association of MFS with thyroid carcinoma. We report a 46-year-old man with known history of MFS who developed an unusual histological variant of papillary thyroid carcinoma. The tumor exhibited a widely invasive florid papillary growth pattern with prominent long villous fronds. Immunohistochemical and molecular analysis revealed a BRAF(V600E) mutation, evidence of aggressive biomarker expression (positivity for HBME-1, cytokeratin 19, galectin-3 and cyclin D1, and loss of p27), and changes associated with TGF-β-related epithelial-to-mesenchymal transition with active phospho-SMAD signaling. We introduce a unique histological pattern of papillary thyroid carcinoma that is associated with MFS. The combination of BRAF(V600E) mutation in the setting of altered TGF-β signaling and weak connective tissue integrity associated with MFS may cooperate and possibly be responsible to form this unique villous morphology with epithelial-to-mesenchymal transition and invasive growth.

Pitfalls in the diagnosis of follicular epithelial proliferations of the thyroid

The diagnosis of follicular epithelial neoplasms is an area of controversy. We provide our experience with common problems that practising pathologists face when confronted with follicular epithelial proliferations. One of the major issues is the recognition of the diagnostic nuclear features of papillary thyroid carcinoma and reactive cytologic atypia. We discuss the definitions of capsular invasion, vascular invasion, and extrathyroidal extension and their implications in cancer diagnosis and staging. We propose unified terminology for benign follicular epithelial proliferations in the setting of multinodular goiter. We also review challenges related to oncocytic change, malignant transformation in benign nodules, focal dedifferentiation, and the application of ancillary tools in thyroid pathology. We believe that this review contains comprehensive and up to date information that will be of value to pathologists who practice surgical pathology of thyroid.

Somatic complex I disruptive mitochondrial DNA mutations are modifiers of tumorigenesis that correlate with low genomic instability in pituitary adenomas

Mitochondrial DNA (mtDNA) mutations leading to the disruption of respiratory complex I (CI) have been shown to exhibit anti-tumorigenic effects, at variance with those impairing only the function but not the assembly of the complex, which appear to contribute positively to cancer development. Owing to the challenges in the analysis of the multi-copy mitochondrial genome, it is yet to be determined whether tumour-associated mtDNA lesions occur as somatic modifying factors or as germ-line predisposing elements. Here we investigated the whole mitochondrial genome sequence of 20 pituitary adenomas with oncocytic phenotype and identified pathogenic and/or novel mtDNA mutations in 60% of the cases. Using highly sensitive techniques, namely fluorescent PCR and allele-specific locked nucleic acid quantitative PCR, we identified the most likely somatic nature of these mutations in our sample set, since none of the mutations was detected in the corresponding blood tissue of the patients analysed. Furthermore, we have subjected a series of 48 pituitary adenomas to a high-resolution array comparative genomic hybridization analysis, which revealed that CI disruptive mutations, and the oncocytic phenotype, significantly correlate with low number of chromosomal aberrations in the nuclear genome. We conclude that CI disruptive mutations in pituitary adenomas are somatic modifiers of tumorigenesis most likely contributing not only to the development of oncocytic change, but also to a less aggressive tumour phenotype, as indicated by a stable karyotype.

Hürthle cells predict hypothyroidism in interferon-γ transgenic mice of different genetic backgrounds

Hürthle cells have long been described in Hashimoto thyroiditis but remain of undetermined significance. We have previously shown that Hürthle cells and hypothyroidism develop in C57BL/6J mice expressing interferon-γ (IFNγ) in the thyroid. To assess the influence of genetic backgrounds on Hürthle cell development, we crossed C57BL/6J IFNγ transgenic mice to 14 strains and analyzed thyroid histopathology and function in a cohort of 389 mice (225 transgenic and 164 wild type) using a multiple linear regression model that also included strain, sex, genotype, and major histocompatibility complex haplotype. We then queried the Johns Hopkins surgical pathology electronic archive for "Hashimoto" and/or "thyroiditis" keywords, reviewed the reports, and reexamined the Hashimoto slides. Hürthle cells were markedly affected by the genetic background: they were prominent and associated with hypothyroidism in the C57BL/6J, C57BL/6ByJ, C57BL/10J, C57BLKS/J, C57L/J, C58/J, and BPN/3J IFNγ transgenic strains, whereas they are mild or absent in the BPH/2J, BPL/1J, LP/J, CBA/J, Balb/cJ, DBA/1J, and NOD/ShiLtJ strains. Hürthle cells were the strongest predictor of hypothyroidism after adjusting for all the other covariates in the regression model. Interestingly, transgenic mice of the BPL/1J, DBA/1J, and NOD/ShiLtJ strains developed a marked accumulation of intrathyroidal brown adipocytes that was significantly associated with improved thyroid function. Hürthle cells were mentioned in 23% of the Hashimoto reports but increased to 79% upon our slide review. This study reports a novel association of Hürhtle cells and brown adipocytes on thyroid function that should prompt a reconsideration of their significance and role in pathogenesis of autoimmune thyroiditis.

Oncocytic lesions (oncocytoma) of the ocular adnexa: report of 15 cases and review of literature

PURPOSE

To describe the clinical, imaging, and pathology features of oncocytic lesions in the ocular adnexa.

METHODS

Retrospective, noncomparative, interventional case series.

RESULTS

Fifteen oncocytic neoplasms (n = 15 patients) were classified as oncocytoma in 14 (93%) and oncocytic hyperplasia in 1 (7%). The mean patient age was 66 years (median = 66, range = 44-82), and 9 (60%) were male. The tumor involved the caruncle (n = 13, 86%), bulbar conjunctiva (n = 1, 7%), and plica semilunaris (n = 1, 7%). All cases were unifocal and most often presented as a painless mass (n = 12, 80%), evolving over a median 6 months (mean = 12, range = 1-48 months). The mean tumor base was 4.1 mm (median = 4.0, range = 1-10), and the tumor was well-circumscribed (n = 14), dark blue (n = 7), and cystic (n = 10). Ultrasound biomicroscopy and anterior segment optical coherence tomography disclosed mixed solid and cystic components. Complete surgical excision was curative without recurrence after a mean follow up of 39 months. Histopathology disclosed columnar cells with copious quantities of intensely eosinophilic cytoplasm in the lining epithelium (oncocytic hyperplasia) and in some cases with cystadenomatous proliferation (oncocytoma).

CONCLUSION

Oncocytic lesions of the ocular adnexae are typically well-circumscribed, cystic lesions that most often involve the caruncle. Surgical excision can be curative. Epithelial cells with copious quantities of intensely eosinophilic cytoplasm characterize oncocytic transformation histopathologically.

Large needle aspiration biopsy histology for preoperative selection of Hürthle cell thyroid nodules

AIMS

To assess whether the large needle aspiration biopsy (LNAB) histological distinction between pure microfollicular nodules and mixed micro-macrofollicular nodules can assist preoperative selection of a Hürthle cell nodule (HCN) discovered by fine needle aspiration cytology (FNAC).

METHODS AND RESULTS

In 24 HCN identified by preoperative FNAC, preoperative LNAB histology was compared with postoperative pathology. FNAC demonstrated seven benign HCN (negative), eight HCN with atypia (positive); seven suspected cancers with HC (positive); and two cancers with Hürthle cells (positive). LNAB showed mixed micro-macrofollicular hyperplastic features in 12 nodules (negative) and a microfollicular structure in 12 nodules (positive), two of which included findings of papillary cancer. Postoperative findings were benign (negative) in 16 patients and malignant (positive) in eight patients. The sensitivity and specificity for FNAC were 87.5% [seven of eight, 95% confidence interval (CI): 47.3-99.7%) and 37.5% (six of 16, 95% CI: 15.2-64.6%], respectively, and for LNAB were 87.5% (seven of eight, 95% CI: 47.3-99.7%) and 68.8% (11 of 16, 95% CI: 41.3-89.0%), respectively. FNAC results were significantly different from postoperative results (McNemar's test, exact two-sided P=0.012), while LNAB results were not (McNemar's test, exact two-sided P=0.219).

CONCLUSIONS

These data suggest that LNAB histology is more accurate than FNAC cytology for the preoperative selection of HCN.

QiSampler: evaluation of scoring schemes for high-throughput datasets using a repetitive sampling strategy on gold standards

Background

High-throughput biological experiments can produce a large amount of data showing little overlap with current knowledge. This may be a problem when evaluating alternative scoring mechanisms for such data according to a gold standard dataset because standard statistical tests may not be appropriate.

Findings

To address this problem we have implemented the QiSampler tool that uses a repetitive sampling strategy to evaluate several scoring schemes or experimental parameters for any type of high-throughput data given a gold standard. We provide two example applications of the tool: selection of the best scoring scheme for a high-throughput protein-protein interaction dataset by comparison to a dataset derived from the literature, and evaluation of functional enrichment in a set of tumour-related differentially expressed genes from a thyroid microarray dataset.

Conclusions

QiSampler is implemented as an open source R script and a web server, which can be accessed at http://cbdm.mdc-berlin.de/tools/sampler/.