Molecular-derived risk of malignancy and the related positive call rate of indeterminate thyroid cytology diagnoses as quality metrics for individual cytopathologists

BACKGROUND

Indeterminate thyroid cytopathology diagnoses represent differing degrees of risk that are corroborated by follow-up studies. However, traditional cytologic-histologic correlation may overestimate the risk of malignancy (ROM) because only a subset of cases undergo resection. Alternatively, some molecular tests provide probability of malignancy data to calculate the molecular-derived risk of malignancy (MDROM) and the positive call rate (PCR). The authors investigated MDROMs and PCRs of indeterminate diagnoses for individual cytopathologists as quality metrics.

METHODS

This study was approved by the Department of Pathology Quality Improvement Program. Thyroid cytopathology diagnoses and ThyroSeq v3 results were retrieved for each cytopathologist for a 2-year period with at least 3 years of follow-up for the atypia of undetermined significance (AUS), follicular neoplasia (FN), and follicular neoplasia, oncocytic-type (ONC) cytopathologic diagnoses. MDROMs and PCRs were compared with reference ROMs and cytologic-histologic correlation outcomes.

RESULTS

The overall MDROMs (and ranges for cytopathologists) for the AUS, FN, and ONC categories were 13.4% (range, 5.8%-20.8%), 28.1% (range, 22.1%-36.7%), and 27.0% (range, 19.5%-41.5%), respectively, and most individual cytopathologists' MDROMs were within reference ROM ranges. However, PCRs more effectively parsed the differences in cytopathologists' ROM performance. Although the overall PCRs were not significantly different across cytopathologists (p = .06), the AUS PCRs were quite different (p = .002). By cytologic-histologic correlation, six of 55 resected cases (10.9%) were falsely negative, and there were no false-positive cases.

CONCLUSIONS

MDROMs and PCRs evaluate concordance with reference ROMs and with one another and provide individual feedback, which potentially facilitates quality improvement.

N-Nitrosomorpholine-induced oncocytic transformation in rat endocrine organs

BACKGROUND

N-Nitrosomorpholine (NMO) is one of the most common N-nitroso compounds. An oncocytic transformation has been demonstrated in renal tubules of NMO-treated rats. In our study, we aimed to investigate the potential transformation of oncocytic cells in 6 endocrine organs, i.e., thyroid, adrenal and pituitary glands, pancreas, testis, and bone, of NMO-exposed rats.

METHODS

Thirty male rats were born and raised. Fifteen of them were given a single dose of 320 mg NMO per kg body weight, dissolved in drinking water, by a gavage tube. At the end of 52 weeks, the animals in both series were killed. Right after the killing, 6 different endocrine organs (hypophysis, thyroid, pancreas, adrenal gland, bone [femur], and testicles) of each animal were excised.

RESULTS

There was no evidence of oncocytic cell development in the control group. In contrast, oncocytes were observed in 8 out of 13 NMO-treated rats: 2 in the adrenal sections, 1 in the thyroid sections, 3 in the pituitary sections, and 2 in the pancreas sections. Thesticle and bone sections were completely normal.

CONCLUSIONS

We showed that NMO induced an oncocytic change in pancreas, thyroid, pituitary, and adrenal glands. To date, no identified specific environmental risk factors that lead to an oncocytic transformation in endocrine glands have been reported previously. Given the increasing prevalence of endocrine-disrupting chemicals in the environment, personal care products, manufactured goods, and food sources, there is a need to advance our understanding of the pathological mechanisms underlying oncocytosis in endocrine organs.

Diagnostic performance of molecular testing in indeterminate (Bethesda III and IV) thyroid nodules with Hürthle cell cytology

BACKGROUND

Indeterminate thyroid nodules with Hürthle cell cytology remain a diagnostic challenge. The low benign call rate and positive predictive value of first-generation molecular tests precluded their use to rule out malignancy. We examined the diagnostic performance of current tests.

METHOD

This subset analysis of our prospective randomized trial compared the benign call rate and positive predictive value of Afirma Gene Sequencing Classifier and Thyroseq v3 in Bethesda III and IV nodules with Hürthle cell cytology. Molecular test samples were obtained at initial fine-needle aspiration (8/2017-7/2022) and reflexively sent for processing.

RESULTS

Molecular testing was performed on 140 Hürthle cell nodules. Of 79 nodules tested with the Afirma Gene Sequencing Classifier, the benign call rate was 84% (66/79). Nine of 66 nodules with benign results were resected, with no malignancies. Twelve of 13 nodules with suspicious results were resected, revealing 3 malignancies-2 papillary thyroid carcinomas and one Hürthle cell carcinoma (positive predictive value 25%). Of 61 nodules tested with Thyroseq v3, the benign call rate was 56% (34/61; (P < .01 versus Afirma Gene Sequencing Classifier). Five of 34 nodules with negative results were resected, with no malignancies. Nineteen of 27 nodules with positive results were resected, revealing 3 malignancies-2 papillary thyroid carcinomas and 1 Hürthle cell carcinoma (positive predictive value 16%).

CONCLUSION

The high benign call rate of current molecular tests in Hürthle cell nodules strengthens their value in enabling patients to avoid surgery.

Papillary cystadenoma of the major salivary gland: A case report and review of literature

Papillary cystadenoma (PC) of the salivary gland is an uncommon benign epithelial neoplasm that shows predominantly multicystic growth pattern with intraluminal papillary proliferation and areas of oncocytic differentiation. We report a case of papillary cystadenoma of the parotid gland in a 44-years-old female. The patient presented with painful nodular swelling in the right parotid region for two months. Ultrasonography revealed a well marginated oval lesion with altered signal intensity involving the superficial lobe. The excision specimen showed a neoplasm with multicystic spaces having papillary projections lined by benign low-grade epithelium and supported by fibrovascular cores. No significant cytological atypia or mitosis was observed. The cells were immunoreactive for Keratin, Keratin 7, and were negative for Keratin 20, AR, HeR2/neu, TTF1, CDX2, and GATA3. p63 and Keratin 5/6 highlighted the myoepithelial cell layer lining the cystic spaces as well as the papillary projections. The Ki-67 proliferation index was 6%. The patient is on close clinical and imaging follow-up for the last 1year and 8 months without any evidence of disease recurrence or metastasis. Rarity of the lesion and distinct histomorphology warrants appropriate knowledge and discussion of the subject.

"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.

Thyroglobulin as a Rapid and Cost-Effective Biomarker for Diagnosis of Thyroid Carcinoma Brain Metastasis: A Case Report of a Patient with Metastatic Hurthle Cell Thyroid Carcinoma

BACKGROUND Brain metastasis of papillary thyroid cancer (PTC) is rare. Treatment of these patients is challenging due to the lack of specific guidelines. Early diagnosis is accompanied by immediate treatment and less morbidity. Total resection of brain lesions may be unattainable when they include infiltration of eloquent areas. This report is of an 81-year-old man who had undergone total thyroidectomy for goiter in the past and presented with metastatic papillary thyroid carcinoma (PTC) to the neck after a gap of 16 years. After two years, the patient developed a solitary cystic brain PTC metastasis associated with raised thyroglobulin (Tg) inside the cystic lesion aspirated during brain surgery. CASE REPORT An 81-year-old male patient was admitted for a space-occupying brain lesion in the right frontal lobe. The patient's history included metastatic disease of PTC to the neck with cervical lymph node metastasis and local recurrence after surgery and radioactive iodine-131 treatment. The patient underwent craniotomy and removal of the lesion. The aspirated fluid was sent for cytological examination and measurement of Tg levels, which were interestingly high. Pathology of the brain lesion revealed infiltration of brain parenchyma from a metastatic lesion characterized by eosinophilic cells with irregular contours forming grooves, resulting in cytoplasmic pseudo-inclusions, an oncotic variant of PTC. CONCLUSIONS This report has shown that residual tissue may be present following total thyroidectomy and may be the origin of PTC with metastasis to the brain. The patient in this study suffered from a brain lesion that could be excised. However, aspiration of cystic compartments could provide a rapid diagnosis in patients with non-removable brain lesions.

Oncocytic sialolipoma of parotid gland: Case report and literature review

Neoplastic lipomatous lesions of the salivary glands constitute ≤0.5% of all the salivary gland tumors. Oncocytic sialolipoma of the parotid glands is extremely uncommon. We report a case of oncocytic sialolipoma of the parotid gland in a 59-year-old male who presented with a gradually increasing swelling of the right parotid. Excisional parotid biopsy performed in view of possible pleomorphic adenoma as suggested on ultrasonography showed histological features consistent with oncocytic sialolipoma. We also described the characteristics of 24 previously reported cases of oncocytic sialolipoma of the parotid gland. The median age of the patients including the present case was 56 years (range 7-89), and 14 were male. The largest and the least reported sizes of the tumor were 7.0 and 1.4 cm, respectively. The left-sided parotid gland was more commonly involved (14/23). Despite its rarity, oncocytic sialolipoma should be considered in lipomatous parotid lesions showing epithelial components with oncocytic changes.

Top Ten Oncocytic Head and Neck Lesions to Contemplate

BACKGROUND

Oncocytes are a component of many metaplastic and neoplastic lesions throughout the head and neck area, primarily originating in salivary/seromucinous glands and the thyroid gland. In addition, other lesions can contain cells that mimic oncocytes (pseudo-oncocytes); these can be of epithelial or non-epithelial origin.

METHODS

Review article.

RESULTS

Oncocytic metaplasia is common in seromucinous glands throughout the upper aerodigestive tract, most notable in the oral cavity, nasopharynx and larynx. The main oncocytic salivary gland neoplasms are Warthin tumor and oncocytoma. Infarction of Warthin tumor may lead to recognition difficulties. Oncocytic subtypes of mucoepidermoid carcinoma and intraductal carcinoma have morphologic and immunohistochemical features that allow distinction from major oncocytic entities. Oncocytic thyroid tumors include adenoma, carcinoma (follicular, papillary and medullary), along with poorly differentiated tumors. Oncocytic papillary sinonasal and middle ear tumors must be distinguished from low grade adenocarcinomas. Pseudo-oncocytic entities include paraganglioma, Langerhans cell histiocytosis, giant cell tumor, rhabdomyoma, and metastatic tumors.

CONCLUSIONS

Correct diagnosis of oncocytic head and neck lesions requires a knowledge of the spectrum of possible entities, their characteristic sites of occurrence, architecture, histomorphology, and immunohistochemistry. Oncocytic subtypes of several newly described entities are now recognized. Both epithelial and non-epithelial mimics of oncocytes exist. The molecular features of oncocytic tumors can be helpful in their diagnosis and understanding their pathogenesis.

Comprehensive Molecular Profiling of Oncocytic Salivary Gland Malignancies

Oncocytic histologic features can be seen in a variety of salivary gland carcinomas. We performed a comprehensive molecular profiling of 15 salivary gland malignancies with oncocytic features (diagnosed as oncocytic carcinoma, carcinoma NOS with oncocytic features, or salivary duct carcinoma with oncocytic features). We reveal multiple novel molecular alterations that have not been previously described in other salivary gland malignancies, including, but not limited to, KEL amplification (13.3%, 2/15), PARP1 amplification (13.3%, 2/15), and EPHB4 amplification (13.3%, 2/15). Alterations in KMT2C (13.3%, 2/15), ERBB3 (13.3%, 2/15), CTNNA1 (13.3%, 2/15), and SMAD4 (20%, 3/15) were also found in this series and have been reported in other salivary gland malignancies. Alterations that have been reported in salivary duct carcinoma were also identified, including TP53 (40%, 6/15) , ERBB2 mutations (13.3%, 2/15) , ERBB2 amplification (13.3%, 2/15), PIK3CA (26.7%, 4/15) , PTEN (20%, 3/15), BRCA2 (20%, 3/15), BRAF (20%, 3/15), CDKN2A/B (20%, 3/15), CDH1 (13.3%, 2/15), and HRAS (13.3%, 2/15). Oncocytic salivary gland malignancies are a molecularly heterogenous group of tumors with partial overlap with salivary duct carcinoma subtypes.

Oncocyte Membrane-Camouflaged Multi-Stimuli-Responsive Nanohybrids for Synergistic Amplification of Tumor Oxidative Stresses and Photothermal Enhanced Cancer Therapy

The combination of various therapeutic modalities has received considerable attention for improving antitumor performance. Herein, an innovative nanohybrid, namely CaO₂@FePt-DOX@PDA@CM (CFDPM), was developed for synergistic chemotherapy/chemodynamic therapy/Ca²⁺ overloading-mediated amplification of tumor oxidative stress and photothermal enhanced cancer therapy. Camouflage of the 4T1 cell membrane enabled CFDPM to escape the immune surveillance and accumulate in the tumor tissue. Ca²⁺, released from CaO₂, could lead to mitochondrial dysfunction and facilitate the production of reactive oxygen species to amplify intracellular oxidative stress. Meanwhile, the increase of H₂O₂ concentration could enhance the efficiency of the chemodynamic therapy (CDT). Moreover, the hypoxic condition could be alleviated remarkably, which is attributed to the sufficient O₂ supply by CaO₂, resulting in the suppression of drug resistance and promotion of the chemotherapeutic effect. The nanohybrids involving Ca²⁺ overloading/CDT/chemotherapy could synergistically amplify the tumor oxidative stresses and remarkably aggravate the death of cancer cells. Significantly, the excellent photothermal conversion performance of CFDPM could further promote the tumoricidal effect. The in vitro and in vivo studies revealed that CFDPM could effectively advance the therapeutic efficiency via the cooperation of various therapeutic modalities to optimize their individual virtue, which would open a valuable avenue for effective cancer treatment.

Mitonuclear genotype remodels the metabolic and microenvironmental landscape of Hürthle cell carcinoma

Hürthle cell carcinomas (HCCs) display two exceptional genotypes: near-homoplasmic mutation of mitochondrial DNA (mtDNA) and genome-wide loss of heterozygosity (gLOH). To understand the phenotypic consequences of these genetic alterations, we analyzed genomic, metabolomic, and immunophenotypic data of HCC and other thyroid cancers. Both mtDNA mutations and profound depletion of citrate pools are common in HCC and other thyroid malignancies, suggesting that thyroid cancers are broadly equipped to survive tricarboxylic acid cycle impairment, whereas metabolites in the reduced form of NADH-dependent lysine degradation pathway were elevated exclusively in HCC. The presence of gLOH was not associated with metabolic phenotypes but rather with reduced immune infiltration, indicating that gLOH confers a selective advantage partially through immunosuppression. Unsupervised multimodal clustering revealed four clusters of HCC with distinct clinical, metabolomic, and microenvironmental phenotypes but overlapping genotypes. These findings chart the metabolic and microenvironmental landscape of HCC and shed light on the interaction between genotype, metabolism, and the microenvironment in cancer.

Synchronous Hürthle cell and medullary thyroid carcinomas

Hürthle cell carcinoma (HCC) and medullary thyroid carcinomas (MTC) are uncommon histological subtypes of thyroid cancers, each accounting for around 3% of all thyroid cancers. A septuagenarian woman with a history of multiple primary cancer diagnoses presented with a growing left-sided neck lump. A diagnostic left thyroid lobectomy was performed, and pathological examination found two separate malignant foci: one HCC and an MTC. The patient developed left-sided HCC nodal metastasis, and following several multidisciplinary team discussions, a right completion lobectomy with left lateral neck dissection was performed, revealing further intrathyroidal MTC and extranodal extension of HCC. We present this as the first reported case of a collision tumour of HCC and MTC, and review the available literature regarding collision tumours and their management.

Follicular and Hurthle Cell Carcinoma: Comparison of Clinicopathological Features and Clinical Outcomes

Background: Follicular thyroid carcinoma (FTC) and Hurthle cell carcinoma (HCC) are rare and aggressive thyroid cancers with limited published data comparing their outcomes or regarding their subtypes. The aim of this study was to describe clinicopathological features and compare clinical outcomes of patients with FTC and HCC based on the 2017 World Health Organization definition and extent of vascular invasion (VI). Methods: We retrospectively studied 190 patients with HCC and FTC primarily treated with surgery at Memorial Sloan Kettering Cancer Center between 1986 and 2015. Patients were classified as minimally invasive (MI), encapsulated angioinvasive with focal VI (EA-FVI), encapsulated angioinvasive with extensive VI (EA-EVI), and as widely invasive (WI). To compare clinical outcomes, patients were grouped as follows: group 1 = FTC-MI and FTC EA-FVI, group 2 = FTC EA-EVI and FTC-WI, group 3 = HCC-MI and HCC EA-FVI, group 4 = HCC EA-EVI and HCC-WI. Outcomes of interest were overall survival (OS), disease-specific survival (DSS), recurrence-free survival (RFS), locoregional recurrence-free survival (LRRFS), and distant recurrence-free survival (DRFS). Outcomes were determined using the Kaplan-Meier method and compared with log-rank test. Results: Patients with HCC (n = 111) were more likely to be older than 55 years old (59% vs. 27%, p < 0.001) with a tendency to present with more extensive VI (33% vs. 19%, p = 0.07) compared with FTC (n = 79). Comparing groups 1, 2, 3, and 4, group 4 patients were more likely to recur (DFS 98%, 93%, 98% vs. 73%, respectively, p = 0.0069). There was no statistically significant difference in OS, DSS LRRFS, or DRFS. Stratified by extent of VI (no, focal, and extensive VI), patients with extensive VI were more likely to recur (RFS 100%, 95%, 77%, p = 0.0025) and had poorer distant control (DRFS: 100%, 95%, 80%, p = 0.022), compared with patients absent or focal VI. Conclusions: Accurate assessment of the extent of VI and tumor phenotype (follicular vs. Hurthle) are essential in identifying patients at higher risk of recurrence.

Malignancy risk in indeterminate thyroid nodules with Hürthle cells: role of autoimmune thyroiditis

INTRODUCTION

Hürthle cells are modified follicular thyroid cells, whose development and proliferation have been related to different stimuli inducing cellular stress. Most thyroid aspirates containing Hürthle cells are classified as indeterminate, although the specific risk of malignancy for this subtype of atypia remains unclear. The aim of our study was to assess if the presence of Hürthle cells in indeterminate thyroid nodules correlates with the risk of malignancy. We further evaluated if this risk can be modified by the presence of an underlying Hashimoto's thyroiditis.

MATERIALS AND METHODS

We retrospectively analyzed all indeterminate thyroid nodules that were surgically treated at our institution between January 2010 and March 2019. For each nodule, we inferred the presence of Hürthle cells in the cytological report. Cytological findings were then correlated with histological reports.

RESULTS

354 indeterminate thyroid nodules were included in the study. The rate of malignancy resulted significantly lower in nodules exhibiting Hürthle cells compared to those negative for this cellular pattern (11.4% vs 22.5%, p = 0.01). Although there was no difference in the rate of malignancy in the whole population according to the presence or absence of Hashimoto's thyroiditis (21.5 vs 18.5%, p = 0.63), the significantly lower prevalence of malignant lesions in nodules with Hürthle cells was confirmed only in the presence of a histologically documented Hashimoto's thyroiditis (6.2% vs 32%, p = 0.005).

CONCLUSIONS

The finding of Hürthle cells in indeterminate thyroid nodules is associated with a low risk of malignancy in patients with an underlying Hashimoto's thyroiditis. The clinical management of these lesions may therefore be more conservative.

Hürthle Cell Carcinoma: Single Center Analysis and Considerations for Surgical Management Based on the Recent Literature

BACKGROUND

Hürthle cell carcinoma (HCC) of the thyroid is rare. There are contrasting data on its clinical behavior. The aim of this study was to describe clinic-pathological features and outcomes of HCC patients at our institution, in order to adapt our surgical management.

METHODS

We retrospectively studied 51 cases of HCC treated at the interdisciplinary endocrine center of the University Hospital of Cologne, Germany between 2005 and 2020.

RESULTS

Patients median age was 63 years (range 29-78) with 64.7% of cases being female. Primary treatment included surgery and postoperative radioiodine therapy with 3.7 GBq in all patients. Surgery consisted of total thyroidectomy in all cases and additional central lymphadenectomy in 90.2% of cases. The median number of harvested lymph nodes was 11 (range 2-31). Lymph node involvement was found in two (4.3%) pT4a tumors. In all other cases (95.7%), central lymphadenectomy was prophylactic and lymph nodes were free of metastasis in final histopathology. Twelve (23.5%) patients with incomplete biochemical response to primary treatment were diagnosed with structural relapse during the course of disease, for which seven (58.4%) underwent resection of isolated cervical metastasis. Histopathology revealed soft tissue implants in all cases and cervical surgery led to biochemical and radiologic cure in only two (28.5%) cases. Five (41.6%) patients developed metastatic disease, followed by systemic therapy in two patients. Vascular invasion of the primary tumor was significantly associated with relapse (p<0.01).

CONCLUSIONS

Recurrence of HCC was common in this study. Given the low rate of lymph node metastases both in this study and in recent literature and the nature of relapse (soft tissue instead of nodal metastasis), the benefit of routine prophylactic central lymph node dissection for HCC remains unclear, especially in the absence of vascular invasion from the primary tumor.

Molecular alterations in Hürthle cell nodules and preoperative cancer risk

Hürthle cell carcinoma (HCC) is a distinct type of thyroid cancer genetically characterized by DNA copy number alterations (CNA), typically of genome haploidization type (GH-type). However, whether CNA also occurs in benign Hürthle cell adenomas (HCA) or Hürthle cell hyperplastic nodules (HCHN), and have diagnostic impact in fine-needle aspiration (FNA) samples, remains unknown. To address these questions, we (1) analyzed 26 HCC, 24 HCA, and 8 HCHN tissues for CNA and other mutations using ThyroSeq v3 (TSv3) next-generation sequencing panel, and (2) determined cancer rate in 111 FNA samples with CNA and known surgical outcome. We identified CNA, more often of the GH-type, in 81% of HCC and in 38% HCA, but not in HCHN. Among four HCC with distant metastasis, all had CNA and three TERT mutations. Overall, positive TSv3 results were obtained in 24 (92%) HCC, including all with ATA high risk of recurrence or metastasis. Among 111 FNA cases with CNA, 38 (34%) were malignant and 73 (66%) benign. A significant correlation between cancer rate and nodule size was observed, particularly among cases with GH-type CNA, where every additional centimeter of nodule size increased the malignancy odds by 1.9 (95% CI 1.3-2.7; P = 0.001). In summary, the results of this study demonstrate that CNA characteristic of HCC also occur in HCA, although with lower frequency, and probability of cancer in nodules with CNA increases with nodule size. Detection of CNA, in conjunction with other mutations and nodule size, is helpful in predicting malignancy in thyroid nodules.

Inherited Thyroid Tumors With Oncocytic Change

Familial non-medullary thyroid carcinoma (FNMTC) corresponds to 5-10% of all follicular cell-derived carcinoma (FCDTC). Oncocytic thyroid tumors have an increased incidence in the familial context in comparison with sporadic FCDTC, encompassing benign and malignant tumors in the same family presenting with some extent of cell oxyphilia. This has triggered the interest of our and other groups to clarify the oncocytic change, looking for genetic markers that could explain the emergence of this phenotype in thyroid benign and malignant lesions, focusing on familial aggregation. Despite some advances regarding the identification of the gene associated with retinoic and interferon-induced mortality 19 (GRIM-19), as one of the key candidate genes affected in the "Tumor with Cell Oxyphilia" (TCO) locus, most of the mutations follow a pattern of "private mutations", almost exclusive to one family. Moreover, no causative genetic alterations were identified so far in most families. The incomplete penetrance of the disease, the diverse benign and malignant phenotypes in the affected familial members and the variable syndromic associations create an additional layer of complexity for studying the genetic alterations in oncocytic tumors. In the present review, we summarized the available evidence supporting genomic-based mechanisms for the oncocytic change, particularly in the context of FNMTC. We have also addressed the challenges and gaps in the aforementioned mechanisms, as well as molecular clues that can explain, at least partially, the phenotype of oncocytic tumors and the respective clinico-pathological behavior. Finally, we pointed to areas of further investigation in the field of oncocytic (F)NMTC with translational potential in terms of therapy.

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.

Genetics, Diagnosis, and Management of Hürthle Cell Thyroid Neoplasms

Hürthle cell lesions have been a diagnostic conundrum in pathology since they were first recognized over a century ago. Controversy as to the name of the cell, the origin of the cell, and even which cells in particular may be designated as such still challenge pathologists and confound those treating patients with a diagnosis of "Hürthle cell" anything within the diagnosis, especially if that anything is a sizable mass lesion. The diagnosis of Hürthle cell adenoma (HCA) or Hürthle cell carcinoma (HCC) has typically relied on a judgement call by pathologists as to the presence or absence of capsular and/or vascular invasion of the adjacent thyroid parenchyma, easy to note in widely invasive disease and a somewhat subjective diagnosis for minimally invasive or borderline invasive disease. Diagnostic specificity, which has incorporated a sharp increase in molecular genetic studies of thyroid tumor subtypes and the integration of molecular testing into preoperative management protocols, continues to be challenged by Hürthle cell neoplasia. Here, we provide the improving yet still murky state of what is known about Hürthle cell tumor genetics, clinical management, and based upon what we are learning about the genetics of other thyroid tumors, how to manage expectations, by pathologists, clinicians, and patients, for more actionable, precise classifications of Hürthle cell tumors of the thyroid.

A case of tumor-to-tumor metastasis of cutaneous malignant melanoma

We report a case of tumor-to-tumor metastasis of a cutaneous malignant melanoma to a synchronous thyroid Hurthle cell carcinoma. A 42-year-old male underwent a biopsy of right inguinal lymphadenopathy which showed metastatic melanoma. The primary lesion was identified on his right posterior leg, and staging workup discovered a synchronous left thyroid lobe nodule concerning for a follicular neoplasm. He underwent excision of the primary melanoma, right inguinal lymphadenectomy, and total thyroidectomy. The resected thyroid contained a 6.6-cm, well-encapsulated left-sided nodule, red-brown in color and homogenous in consistency, with areas of focal hemorrhage and no grossly identifiable calcification. Microscopically, large tumor cells with distinct cell borders were present, with deeply eosinophilic and granular cytoplasm, large nuclei with prominent nucleoli, and loss of polarity consistent with oncocytes. A microscopic single focus of vascular invasion was identified, and a diagnosis of angioinvasive Hurthle cell carcinoma was made. Within the Hurthle cell carcinoma, multiple deposits of metastatic melanoma were seen. These findings were indicative of tumor-to-tumor metastasis of the cutaneous melanoma to the angioinvasive Hurthle cell carcinoma. Our findings show the ability of melanoma to metastasize to a pre-existing neoplasm.

The Oncocytic Variant of Poorly Differentiated Thyroid Carcinoma Shows a Specific Immune-Related Gene Expression Profile

BACKGROUND

Poorly differentiated thyroid cancer (PDTC) is a rare, follicular cell-derived neoplasm with an unfavorable prognosis. The oncocytic variant of PDTC may be associated with even more adverse outcome than classical PDTC cases, but its specific molecular features are largely unknown. Our aim was to explore the immune-related gene expression profile of oncocytic and classical PDTC, in correlation with clinical and pathological characteristics (including programmed death ligand 1 [PD-L1] expression) and outcome, and in comparison with a control group of well-differentiated follicular carcinomas (WDFCs), including conventional follicular carcinomas (FTCs) and Hürthle cell carcinomas (HCCs).

METHODS

A retrospective series of 48 PDTCs and 24 WDFCs was analyzed by means of NanoString technology employing the nCounter PanCancer Immune Profiling panel. Gene expression data were validated using quantitative real-time polymerase chain reaction.

RESULTS

Oncocytic PDTCs showed a specific immune-related gene expression profile, with higher expression of LAIR2, CD274, DEFB1, IRAK1, CAMP, LCN2, LY96, and APOE, and lower expression of NOD1, as compared to conventional PDTCs. This molecular signature was associated with increased intratumoral lymphocytic infiltration, PD-L1 expression, and adverse outcome. Three of these genes, CD274, DEFB1, and IRAK1, as well as PD-L1 expression, were also the hallmarks of HCCs as compared to FTCs. By contrast, the panel of genes differentially regulated in PDTCs as compared to WDFCs was unrelated to the oncocytic phenotype.

CONCLUSIONS

Our results revealed a distinctive immune-related gene expression profile of oncocytic PDTC and confirmed a more aggressive outcome in this cancer subtype. These findings may provide guidance when exploring novel immunotherapeutic options for oncocytic PDTC patients.

Parotid gland oncocytic carcinoma: A rare entity in head and neck region

Oncocytic carcinoma of the salivary gland is an uncommon tumour in the head and neck region. Owing to its rarity, identifying the histopathological features of a malignant tumour can be difficult and challenging. We report a case of a 70-year-old man who presented with a left facial weakness for six months in a background history of left parotid swelling over the past 10 years. Clinical examination revealed a 3x3cm left parotid mass and grade 4 facial nerve palsy. Fine needle aspiration of the mass showed scattered cohesive, monolayered sheets of uniform oncocytic cells. Subsequently, a left total parotidectomy and selective neck dissection were performed. Histological examination showed sheets of small oncocytes with minimal nuclear atypia. Evidence of nerve entrapment, capsular invasion and perivascular permeation were identified in focal areas. Thus, a final diagnosis of oncocytic carcinoma was rendered.

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.

Thyroid nodules with Hürthle cells: the malignancy risk in relation to the FNA outcome category

PURPOSE

The aim was to find whether the presence of Hürthle cells (HC) in a smear influences the categorization of FNA results or the risk of malignancy (RoM) of particular categories of cytological diagnosis.

METHODS

25,220 FNA performed in a single center in years 2005-2017 were analyzed. Almost all the examined patients were exposed to moderate iodine deficiency for most of their lives. The distribution of FNA outcome categories was compared between two groups: with or without HC (HC and non-HC). The RoM was evaluated on the basis of postoperative histopathological examination (3082 patients).

RESULTS

HC were found in 7.5% of diagnostic FNA. HC nodules were classified into categories II (78.2% vs. 91.9%, p < 0.0000) and VI (0.4% vs. 1.2%, p = 0.0017) less often than non-HC nodules, but more frequently to categories III (14.4% vs. 5.8%, p < 0.0000), IV (11.2% vs. 0.9%, p < 0.0000) and V (1.5% vs. 0.8%, p = 0.0013). There were no significant differences in RoM between HC and non-HC nodules. The RoM in HC and non-HC nodules of particular categories of the Bethesda system was as follows: II: 1.8% vs. 0.8%, III: 9.7% vs. 3.8% when only the last FNA was considered and 10.8% vs. 6.4% when the category III in any performed FNA was considered; IV: 12.7% vs. 10.9%; V: 41.7% vs. 58.2%; and VI: 100% vs. 96.9%.

CONCLUSIONS

HC nodules are classified into categories of equivocal cytological outcomes more often than nodules without HC. Nevertheless, the presence of HC in a smear does not significantly affect the RoM of FNA categories.

Sporadic renal hybrid oncocytic/chromophobe tumor in a young man: A case report

RATIONALE

Hybrid oncocytic/chromophobe tumor (HOCT) is defined as tumor composed of renal oncocytoma (RO) and chromophobe renal cell carcinoma (CHRCC). Sporadic HOCT is extremely rare, the preoperative diagnosis is difficult, and no guidelines for clinical therapy. We report a case who is the youngest male patient of sporadic HOCT in the world, review the previously reported cases, and share the clinical features, diagnosis, treatment, and prognosis of HOCT.

PATIENT CONCERNS

A 30-year-old man was admitted with the complaints of incidental right renal tumor detected by abdominal ultrasound. He had no complaints of urological symptoms, abdominal pain, osphyalgia, and hematuria. Abdominal contrast-enhanced computed tomography revealed an 85 mm × 80 mm × 80 mm unilateral and solid renal mass, and no findings of metastases.

DIAGNOSIS

The preoperative diagnosis was right renal tumor.

INTERVENTIONS

Laparoscopic right radical nephrectomy was performed.

OUTCOMES

Histopathology demonstrated a mixture of cells with the morphologic features of those seen in CHRCC and RO. The patient was final diagnosed as sporadic HOCT. After follow-up of 14 months, the patient had no complaints and evidence of disease recurrence.

LESSONS

Sporadic HOCT is extremely rare. It is possible that core biopsy could improve diagnostic accuracy. Laparoscopic radical nephrectomy or nephron sparing surgery should be considered the clinical therapy of the sporadic HOCT patients. The clinical behavior of HOCT is still entirely uncertain and should be proved by studies with available long follow-up.

Identification of Hürthle cell cancers: solving a clinical challenge with genomic sequencing and a trio of machine learning algorithms

BACKGROUND

Identification of Hürthle cell cancers by non-operative fine-needle aspiration biopsy (FNAB) of thyroid nodules is challenging. Resultingly, non-cancerous Hürthle lesions were conventionally distinguished from Hürthle cell cancers by histopathological examination of tissue following surgical resection. Reliance on histopathological evaluation requires patients to undergo surgery to obtain a diagnosis despite most being non-cancerous. It is highly desirable to avoid surgery and to provide accurate classification of benignity versus malignancy from FNAB preoperatively. In our first-generation algorithm, Gene Expression Classifier (GEC), we achieved this goal by using machine learning (ML) on gene expression features. The classifier is sensitive, but not specific due in part to the presence of non-neoplastic benign Hürthle cells in many FNAB.

RESULTS

We sought to overcome this low-specificity limitation by expanding the feature set for ML using next-generation whole transcriptome RNA sequencing and called the improved algorithm the Genomic Sequencing Classifier (GSC). The Hürthle identification leverages mitochondrial expression and we developed novel feature extraction mechanisms to measure chromosomal and genomic level loss-of-heterozygosity (LOH) for the algorithm. Additionally, we developed a multi-layered system of cascading classifiers to sequentially triage Hürthle cell-containing FNAB, including: 1. presence of Hürthle cells, 2. presence of neoplastic Hürthle cells, and 3. presence of benign Hürthle cells. The final Hürthle cell Index utilizes 1048 nuclear and mitochondrial genes; and Hürthle cell Neoplasm Index leverages LOH features as well as 2041 genes. Both indices are Support Vector Machine (SVM) based. The third classifier, the GSC Benign/Suspicious classifier, utilizes 1115 core genes and is an ensemble classifier incorporating 12 individual models.

CONCLUSIONS

The accurate algorithmic depiction of this complex biological system among Hürthle subtypes results in a dramatic improvement of classification performance; specificity among Hürthle cell neoplasms increases from 11.8% with the GEC to 58.8% with the GSC, while maintaining the same sensitivity of 89%.

An Insight into the Utility of Sub-Categorisation of Atypia of Undetermined Significance for Risk Stratification: A Retrospective Study on an Indian Cohort with Histopathological Correlation

BACKGROUND

Atypia of undetermined significance or follicular lesion of undetermined significance (AUS/FLUS) criterion in thyroid fine-needle aspirates (FNAs) has been a heterogeneous entity with much inter-observer variation. Sub-categorisation of AUS/FLUS has been observed to play an effective role in risk stratification. We aimed to validate AUS/FLUS sub-categorisation in correlation with the spectrum of malignancy.

STUDY DESIGN

Subjects included patients with AUS/FLUS diagnosed between January 2015 and December 2016. AUS/FLUS cases were sub-categorised into those exhibiting (1) architectural atypia, (2) cytological atypia, (3) architectural and cytological atypia, (4) AUS with Hürthle cells, and (5) AUS not otherwise specified (AUS-NOS). Each sub-category was correlated with their corresponding incidence of malignancy in surgical resections.

RESULT

The overall incidence of AUS/FLUS in our centre was 13% (132/1,018). On retrospective review of 117 patients with AUS/FLUS, smears with cytological atypia showed a higher incidence of malignancy (78.3%) than those with architectural atypia (75.3%). AUS/FLUS cases with both cytological and architectural atypia had a malignancy rate of 71.4%.

CONCLUSION

AUS/FLUS cases with cytological atypia had a higher risk of malignancy than those with architectural atypia. The sub-categorisation of AUS/FLUS is diagnostically important for the proper risk stratification of patients.

Risk of Malignancy and Risk of Neoplasia in the Bethesda Indeterminate Categories: Study on 4,532 Thyroid Fine-Needle Aspirations from a Single Institution in India

OBJECTIVES

To determine the frequency of category 3 (atypia of undetermined significance [AUS]/follicular lesion of undetermined significance [FLUS]), category 4 (follicular neoplasm), and category 5 (suspicious for malignancy) of The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC), the risk of malignancy (ROM) and the risk of neoplasia (RON) in these categories.

STUDY DESIGN

A retrospective 6-year audit of 4,532 thyroid fine-needle aspirations (FNA) reported as per the TBSRTC from a single institution with cytohistological correlation in 335 cases.

RESULTS

The frequency of categories 3, 4, and 5 was 2.5, 3.9, and 0.5%, respectively; the upper and lower bound estimates of ROM being 58.3, 23.6, 75% and 5.1, 5, and 12.5%, respectively. AUS/FLUS (n = 116) cases were subcategorized as AUS, AUS-HC (Hürthle cell), AUS-PTC (AUS-papillary thyroid carcinoma not excluded), FLUS, FLUS-FH (favor hyperplasia), FLUS-HC, and FLUS-PTC. The AUS/FLUS malignancy ratio was 1:3.8. The sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of FNA thyroid was 80.5, 85.9, 80.7, 85.7, and 82.4%, respectively.

CONCLUSION

Implementation of TBSRTC aided in achieving internal quality control in reporting thyroid FNA cytology. The AUS/FLUS frequency was 2.5%, which is at the lower range of the recommended rate and was associated with a higher than recommended upper bound estimate, but a comparable lower bound estimate of ROM.

Hashimoto's thyroiditis associated with thyroid adenoma with Hürthle cells - case report

Chronic thyroiditis may present a focal lesion, often-palpable abnormality, simulating nodular disease. The number and morphology of the Hürthle cells (HC) vary in the thyroid aspirate. Distinguishing between neoplastic and non-neoplastic HC lesions is difficult when using the fine-needle aspiration cytology (FNAC). We present the case of a 46-year-old female with a large right nodular goiter and hypothyroidism and high titer of anti-thyroid peroxidase antibody (TPO). The thyroid ultrasound showed a large well-defined nodule (more than 6.8 cm) with hypoechogenicity and microcalcification. FNAC (Mayo Clinic technique) smears revealed HC arranged in flat sheets in 75% in the sample with moderate nuclear pleomorphism, abundant granular cytoplasm showing eosinophilia and well-defined cytoplasmic borders, a lightly eccentric enlarged nuclei; the colloid was reduced and lymphocytes were also described. The final histological examination revealed that oncocyte cell proliferation is limited to the thyroid parenchyma and does not exceed the capsule and has no vascular invasion. The presence of lymphocytic infiltration and a performing FNAC (like Mayo Clinic technique) is absolutely necessary in a focal autoimmune thyroiditis in order to exclude HC carcinoma.

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.

Elastosonography scoring and strain index of thyroid nodules with Hurthle cells

BACKGROUND

This study evaluated the effectiveness of elastosonography (ES) scoring and strain index (SI) in diagnosing patients with thyroid nodules composed primarily of Hurthle cells.

METHODS

This study retrospectively analyzed 57 patients with thyroid nodules composed predominantly of Hurthle cells on fine needle aspiration cytology (FNAC). Patients were evaluated by thyroid ultrasonography (US), ES scoring, SI, US guided FNAC, and histopathology.

RESULTS

Histopathologically, 12 (21.1%) nodules were malignant and 45 (78.9%) were benign. Mean age, sex distribution, thyroid function tests, and morphologic features on US were similar in the malignant and benign groups. Mean SI (40.98±31.28 vs 21.24±25.47, p=0.027) and thyroid peroxidase antibody (anti-TPOab) positivity (p=0.004) were significantly higher in malignant than in benign nodules. Receiver operating curve (ROC) analysis showed that an SI cutoff of 10.326 had a sensitivity of 91.7% and a specificity of 49%, and an SI cut-off of 64.807 had a specificity of 91.1% and a sensitivity of 25%. The optimal SI cut-off value, 17.877, had a sensitivity of 66.7%, a specificity of 66.7%, a positive predictive value (PPV) of 34.8%, a negative predictive value (NPV) of 88.2%, and an area under the ROC curve of 73.1±0.074% (95% CI: 58.7-87.6.5%). The sensitivity, specificity, PPV, NPV and diagnostic accuracy of ES scoring were 41.6%, 91.1%, 55.5%, 85.4% and 80.7%, respectively.

CONCLUSIONS

This is the first study to investigate ES scoring and SI in nodules composed predominantly of Hurthle cells on FNAC. ES scoring and SI may add some contribution to ultrasonography in the characterization of thyroid nodules with Hurthle cells.

Cytotechnologist Performance for Screening Hürthle Cell Atypia in Indeterminate Thyroid Fine-Needle Aspirates

OBJECTIVES

We have previously shown that specimens diagnosed as containing Hürthle cells have a 12% chance of being malignant if they are classified as atypia of undetermined significance (AUS-HC). The identification of Hürthle cells by cytotechnologists (CTs) during screening can improve cytopathologist efficiency and may prevent diagnostic errors due to the oversights of focal findings. Here, we examine the performance of our institutional CTs when screening for Hürthle cell atypia in thyroid fine-needle aspiration (FNA) specimens.

STUDY DESIGN

Information on 8,814 thyroid cytopathology specimens was retrieved for a 10-year period. Specimens were screened by 1 of 11 CTs. A subsample of cases was categorized either as AUS-HC or suspicious for Hürthle cell neoplasm.

RESULTS

AUS-HC screening diagnoses were more likely to be downgraded to benign but less likely to be upgraded compared to AUS diagnoses with nuclear or microfollicular atypia. AUS-HC represents almost all papillary thyroid carcinoma (PTC) screening diagnoses downgraded to the AUS category, which suggests that even low levels of Hürthle cell atypia can result in PTC being included in the differential diagnosis.

CONCLUSION

Overall, there are few major discrepancies between CT and pathologist diagnoses for specimens containing Hürthle cell atypia.

Oxyphil Cell Parathyroid Adenomas Causing Primary Hyperparathyroidism: a Clinico-Pathological Correlation

Oxyphil cell parathyroid adenomas (OPA) are considered to be an uncommon cause of primary hyperparathyroidism (PHPT), and were historically thought to be clinically silent. It has been our clinical impression that these adenomas present more often than previously thought and may manifest a more severe form of primary hyperparathyroidism than classical adenoma. The aim of this study was to describe the incidence and clinical presentation of OPA. An observational case-control study was undertaken. The study group comprised patients undergoing parathyroidectomy for PHPT where the final pathology confirmed OPA. The controls were made up of an age- and sex-matched group of patients having parathyroidectomy in the same time period where the final pathology confirmed a classical or non-oxyphil adenoma. OPA were defined as parathyroid tumours containing >75% oxyphilic cells. The OPA cases were obtained by reviewing all histopathology slides over an 11-year period (2002-12) where the reports contained the words 'oxyphil' or 'oxyphilic' parathyroid adenomas. These were then reviewed by two independent pathologists to confirm a diagnosis of OPA. The primary outcome measures were preoperative serum calcium and parathyroid hormone (PTH) levels. Secondary outcome measures were symptoms at presentation, accuracy of preoperative localization studies, parathyroid gland weight following surgery, and type of surgery undertaken. In the period 2002-2012, 2739 patients underwent surgery for PHPT. Following pathological review, 91 cases were confirmed as being OPA and formed the study group. A control group (n = 91) from the same period was selected following matching on the basis of age at presentation and sex. OPA were associated with higher preoperative serum calcium (10.84 versus 10.48 mg/dL, p < 0.001) and parathyroid hormone (139 versus 64 ng/L, p < 0.001). At presentation, a lower proportion of OPA cases had asymptomatic disease (15 versus 29%, p = 0.03). There was a trend toward a higher rate of renal calculi at presentation in the OPA group (9 versus 3%, p = 0.07). Preoperative ultrasound was less accurate in localization of OPA when compared with classical adenoma. The rate of minimally invasive surgery was 67% for OPA and 78% for the control group (p = 0.06). All patients were cured of hypercalcaemia at 6-month follow up. There was no significant difference in the weight of removed parathyroid tissue between the groups (868 mg for OPA versus 789 mg for the control group, p = 0.6). OPA are frequently symptomatic and are associated with higher preoperative serum calcium and parathyroid hormone levels than classical types of parathyroid adenomas. OPA are less likely to be localised on preoperative ultrasound examination.

Urothelial carcinoma with oncocytic features: an extremely rare case presenting a diagnostic challenge in urine cytology

Recognizing histological variants in urothelial carcinoma (UC) is important because some may be associated with different clinical outcomes and/or therapeutic approaches; being aware of unusual histological variants may also be crucial in preventing diagnostic misinterpretations. Histological variants based on cytoplasmic features, such as clear-cell, plasmacytoid, rhabdoid, and lipoid-rich variants, are described in invasive UC; however, these cytoplasmic features are not formally defined and not usually encountered in non-invasive UC. Oncocytic cytoplasm has not been well described in either invasive or non-invasive UC. Herein, we report an exceedingly rare case of UC with oncocytic features arising in the right renal pelvis, which presented a diagnostic challenge in urine cytology due to the relatively low nuclear-to-cytoplasmic ratio; however, it could definitively be diagnosed using histological specimens. UC diagnosis is based on the presence of papillary architecture and widespread p53 nuclear accumulation, suggesting malignancy. An oncocytic tumor is generally considered to be not actively dividing, as shown by the low Ki-67 labeling index in this case. In spite of the low proliferative activity, the possibility of intravesicle recurrence (IVR) should be considered since positive preoperative cytology of upper tract UC is a risk factor for IVR after nephroureterectomy.

Performance of the Afirma Gene Expression Classifier in Hürthle Cell Thyroid Nodules Differs from Other Indeterminate Thyroid Nodules

BACKGROUND

The recently introduced Afirma gene expression classifier (AGEC) provides binary results (benign or suspicious) to guide management of cytologically indeterminate thyroid nodules. The AGEC is intended to reduce unnecessary surgeries for benign nodules, and management algorithms favor surgery for suspicious results. Limited data are available on the performance of this test for Hürthle cell nodules (HCNs). This study hypothesized that a predominance of Hürthle cells leads to an increased rate of suspicious AGEC results with a potential for overtreatment, despite a relatively low risk of malignancy.

METHODS

The pathology databases from three tertiary care facilities were queried from 2010 to 2014 for fine-needle aspirates (FNAs) diagnosed as suspicious for Hürthle cell neoplasm (SHCN) or atypia of undetermined significance/follicular lesion of undetermined significance concerning for Hürthle cell neoplasm (AFHCN). Cytology diagnoses were rendered internally prior to AGEC testing. The patient demographics, FNA diagnosis, AGEC result, surgical procedure, and pathologic outcomes were recorded.

RESULTS

The cohort consisted of 134 patients with HCNs. Prior to AGEC availability, 62 patients underwent surgery: 81% (50/62) of patients had surgery, and 34% (17/50) of the resected index nodules were malignant. After introduction of the AGEC, 72 patients underwent AGEC testing: 65% (47/72) of patients had surgery, and 13% (6/46) of the resected nodules were malignant. Thirty-two percent (23/72) of patients had a benign AGEC result and did not undergo surgery, and 4% (3/72) had surgery despite a benign AGEC result with benign final pathology, whereas 63% (45/72) of patients had suspicious AGEC results, with 96% of these patients (43/45) undergoing surgery, and 14% (6/43) of these index nodules were malignant.

CONCLUSIONS

While 32% of tested patients declined surgery based on a benign AGEC, 86% of patients with suspicious AGEC findings had unnecessary surgery, reflecting a substantially lower rate of malignancy from what was previously reported for all indeterminate nodules. Given the approximate pretest malignancy risk of 25-35% for an FNA diagnosis of SHCN or AFHCN, a suspicious AGEC diagnosis does not increase the probability of malignancy in an HCN, and patients should be counseled accordingly.

Poorly differentiated oncocytic (hürthle cell) follicular carcinoma: an institutional experience

The proposed diagnostic criteria for poorly differentiated thyroid carcinoma (known as the Turin classification) were defined based on growth pattern (solid, trabecular, or insular) and high-grade morphologic features (nuclear pleomorphism, mitoses including abnormal forms, and coagulative tumor necrosis). The development of this classification specifically did not include tumors with oncocytic or Hürthle cell cytology, and only sparse literature describing poorly differentiated oncocytic carcinomas is available. In this study, we examined a cohort of 284 cases of oncocytic follicular carcinoma/Hürthle cell carcinoma (OFC/HCC) and identified 17 cases of oncocytic variant of poorly differentiated carcinoma (OV-PDTC) based on Turin criteria. Compared to minimally invasive and angioinvasive OFC/HCC, these tumors arose in older patients (range 44-88 years; average 71 years), were larger (average size 4.5 cm), and all had extensive vascular invasion (5-15 foci), and coagulative tumor necrosis and the tumor cells were arranged in a trabecular or solid growth pattern. All showed an admixture of oncocytic follicular/Hürthle cells arranged in solid and trabecular growth pattern. Aggregates of small sized cells with minimal eosinophilic cytoplasm, comprising 10-20% of the entire tumor mass were also seen in 16/17 cases. Clinical follow-up was available in 12 cases and ranged from 6 to 120 months (average 41 months). Distant metastases were seen in 10/12 (83%) patients; two had lung and one had bone metastases at the time of thyroid surgery, and four subsequently developed cervical lymph node metastases. Two patients died of disease, and ten are alive either with or free of tumor. The OV-PDTC is a distinct entity which can be identified based on Turin criteria and the presence of a distinct "small cell" component. It is frequently associated with regional recurrence and distant metastases and can lead to tumor-related demise.

Hurthle cells in fine needle aspiration cytology of the thyroid: a potential diagnostic dilemma?

Hurthle cells are not uncommonly encountered in thyroid fine needle aspiration cytology (FNAC) smears. They are easily recognized by their distinct cytomorphology in cytological preparations, i.e. large, polygonal cells displaying uniform, rounded nuclei, often prominent nucleoli and abundant granular cytoplasm. Hurthle cells can be seen in both non-neoplastic and neoplastic thyroid lesions which can pose diagnostic dilemma to cytopathologists, especially when the lesions are focally sampled. We describe a case of solitary thyroid nodule in a 46-year-old male, whose aspirates comprised predominantly of Hurthle cells exhibiting nuclear features suspicious of papillary carcinoma, which turned out to be Hurthle cell carcinoma on subsequent histological sections. The potential diagnostic pitfalls of Hurthle cell lesions and associated conditions in thyroid FNA are discussed. The presence of Hurthle cell change in a wide variety of thyroid lesions can be diagnostically challenging. However, accurate diagnosis can still be made with careful observation of the predominant cell population, nuclear features and whether there is abundant colloid or lymphocytes in the background.

[A case of parathyroid adenoma with oxyphil cells]

A 56-year-old woman who was undergoing dialysis for renal failure that occurred 4 years previously was identified with hypercalcemia and high levels of intact parathyroid hormone (iPTH), as observed on blood analysis results. Blood analysis also indicated high levels of Ca (12.7 mg/dL) and parathyroid hormone (PTH 1,280 ng/mL). Secondary hyperparathyroidism was suspected to be the cause of hypercalcemia. Cervical neck ultrasonography revealed a 13-× 4-mm hypoechoic mass in the lower left pole of the thyroid gland. Tc-99 metaiodobenzylguanidine (MIBG )imaging revealed aberrant accumulation at the lower region of the left accessory thyroid. Cervical neck computed tomography revealed a 12-mm mass at the inferior pole of the left thyroid gland. Considering the above observations, a diagnosis of lower left parathyroid adenoma was made. Lumpectomy was performed, and the final pathology report indicated oxyphilic adenoma. Chief cells are often observed in parathyroid adenoma, but, to our knowledge, this is the first case of a parathyroid adenoma with oxyphil cells.

Squamous cell carcinoma of the larynx arising in multifocal pharyngolaryngeal oncocytic papillary cystadenoma: a case report and review of the literature

We report on a rare case of a laryngeal carcinoma arising in a multifocal pharyngolaryngeal oncocytic papillary cystadenoma (OPC). The disease of a 63-year-old man is well documented by computed and positron emission tomography, histology, and electron microscopy. We could show that an OPC can even develop in the pharynx. The coexistence of both tumors makes this a challenging diagnosis for pathologists. Treated by surgery and radiotherapy, both lesions dissolved. Based on the literature available, we discuss the theory that the laryngeal carcinoma might be the result of a true metaplasia facilitated by chronic irritation and recommend a regular follow-up for OPC too. As in benign oncocytic lesions, we could show that the detection of numerous mitochondria is a diagnostic indicator for malignant variants as well.

[An expert system for differential diagnosis of medullary and oxyphilic cell thyroid carcinoma]

OBJECTIVE

To reveal the quantitative regularities of pathological changes in the nuclei and aggregates of C and B cells and to build an expert system on their basis for the differential diagnosis of medullary and oxyphilic cell thyroid carcinoma.

MATERIAL AND METHODS

Puncture smears with histologically verified medullary (C cell) carcinoma and oxyphilic cell (B cell) carcinoma were investigated. The nuclei and aggregates of C cells and B cells (Hürthle cells, oncocytes) were morphometrically examined with a computer color image analyzer on the basis of a light microscope and a digital photo camera.

RESULTS

The quantitative regularities of the degree of C and B cell aggregation in medullary and oxyphilic cell thyroid carcinoma were found by morphometry. The threshold values for the aggregates in the comparison groups and their weight coefficients formed the basis for the expert system to differentially diagnose medullary and oxyphilic cell carcinoma at the initial stages of patient examination. The clinical trials showed the high efficiency of the developed expert system.

Elevated blood Hsp60, its structural similarities and cross-reactivity with thyroid molecules, and its presence on the plasma membrane of oncocytes point to the chaperonin as an immunopathogenic factor in Hashimoto's thyroiditis

The role Hsp60 might play in various inflammatory and autoimmune diseases is under investigation, but little information exists pertaining to Hashimoto's thyroiditis (HT). With the aim to fill this gap, in the present work, we directed our attention to Hsp60 participation in HT pathogenesis. We found Hsp60 levels increased in the blood of HT patients compared to controls. The chaperonin was immunolocalized in thyroid tissue specimens from patients with HT, both in thyrocytes and oncocytes (Hurthle cells) with higher levels compared to controls (goiter). In oncocytes, we found Hsp60 not only in the cytoplasm but also on the plasma membrane, as shown by double immunofluorescence performed on fine needle aspiration cytology. By bioinformatics, we found regions in the Hsp60 molecule with remarkable structural similarity with the thyroglobulin (TG) and thyroid peroxidase (TPO) molecules, which supports the notion that autoantibodies against TG and TPO are likely to recognize Hsp60 on the plasma membrane of oncocytes. This was also supported by data obtained by ELISA, showing that anti-TG and anti-TPO antibodies cross-react with human recombinant Hsp60. Antibody-antigen (Hsp60) reaction on the cell surface could very well mediate thyroid cell damage and destruction, perpetuating inflammation. Experiments with recombinant Hsp60 did not show stimulation of cytokine production by peripheral blood mononuclear cells from HT patients. All together, these results led us to hypothesize that Hsp60 may be an active player in HT pathogenesis via an antibody-mediated immune mechanism.

Fine-needle aspiration cytology of thyroid nodules with Hürthle cells: cytomorphologic predictors for neoplasms, improving diagnostic accuracy and overcoming pitfalls

OBJECTIVES

Hürthle cells (HCs) are follicular-derived oncocytic cells seen in a variety of neoplastic and nonneoplastic pathologic entities of the thyroid gland. This study was to report our experience of the surgical outcome on the finding of HCs on fine-needle aspiration biopsies (FNABs) of thyroid nodules, to identify cytologic predictors of HC neoplasms and an attempt to overcome diagnostic pitfalls.

STUDY DESIGN

This was a retrospective study of all FNAB of thyroid nodules with findings of HCs with subsequent surgical resection. The FNAB slides of 70 thyroid nodules were blindly reviewed for specific cytomorphologic characteristics. The cytologic findings were correlated with the corresponding final surgical pathology diagnosis.

RESULTS

The patients ranged in age from 25 to 78 years with a male:female ratio of 1:2. There were 19 false-negative and 4 false-positive cases. Overall high cellularity, scant colloid and >90% HCs on FNAB are consistently seen in a neoplastic HC process. All cases of Hashimoto's thyroiditis were associated with prominent nucleoli and 92% of cases demonstrating transgressing vessels were neoplastic.

CONCLUSION

Diagnostic accuracy can be improved by following the current Bethesda classification system. A constellation of cytomorphologic features in conjunction with clinical findings can be considered a strong predictor of a neoplastic process.

Morphological and immunohistochemical criteria of tissue response to radiotherapy in rectal cancer

AIM

Given the context that rectal tumours respond to a certain degree to radiotherapy, a necessity arises for estimating a tumour's capacity to react to radiation from the very moment of diagnostic biopsy.

MATERIAL AND METHODS

We have histologically and immunohistochemically analysed tissues coming from 52 patients with rectal adenocarcinomas.

RESULTS

Of the studied parameters, the ones presenting significant variation under radiotherapy in terms of statistics(p 0.05) were: colloid type (p=0.001), EGFR in the tumour(p=0.00045), EGFR in the normal epithelium (p=0.0017),VEGF in the tumour (p=0.0132) and VEGF in the tumour stroma (p=0.030).

CONCLUSIONS

Our study follows the same trends as the medical literature we have consulted regarding the variation of EGFR and VEGF with radiotherapy, and the distinct note of our study relies in the observation that normal stroma in case of rectal tumors also reacts to radiotherapy, sometimes more aggressively than the tumor itself, especially in which concerns the nerve and muscle fibers.

Oncocytic glioblastoma: a glioblastoma showing oncocytic changes and increased mitochondrial DNA copy number

Ten cases of glioblastomas showing oncocytic changes are described. The tumors showed mononuclear to multinuclear cells and abundant, granular, eosinophilic cytoplasm. The cytoplasm of these same cells was filled by strongly immunoreactive mitochondria. At ultrastructure, numerous mitochondria, some of which were large, were evidenced in the cytoplasm of neoplastic cells. Finally, 9 of 10 of these cases had a significantly high mitochondrial DNA content compared with control tissue (P < .01). It seems that, for these tumors, the designation of oncocytic glioblastoma is appropriate. To the best of our knowledge, oncocytic changes have not been previously reported in such neoplasms. Oncocytic glioblastomas have to be added to the long list of various tumors that can manifest "unexpected" oncocytic changes in different organs. Albeit failing to show statistical significance (log-rank test, P = .597; Wilcoxon test, P = .233), we observed a trend for longer median survival in oncocytic glioblastomas, when compared with "ordinary" glioblastomas (median survival of 16 versus 8.7 months). Thus, it seems that the definition of neoplasms showing oncocytic changes, currently based on classic morphological parameters (ie, histology, ultrastructure, and immunohistochemistry), can be expanded by including the quantitative assessment of mitochondrial DNA content.