Differential diagnosis of Hürthle cell neoplasms on fine needle aspirates. Can we do any better with morphometry?

Unraveling the Enigma: A Five-Year Comprehensive Analysis of Hurthle Cell Tumors in South India's Tertiary Care Center

BACKGROUND

Hurthle cell tumors of the thyroid gland constitute a rare and enigmatic group of neoplasms, characterized by the presence of Hurthle cells exhibiting abundant eosinophilic cytoplasm and numerous mitochondria. Despite their low incidence, they pose diagnostic challenges and display diverse clinical outcomes. This study aims to provide a comprehensive analysis of the clinicopathological profile of Hurthle cell tumors within a tertiary care center in South India.

METHODS

Through a retrospective approach, we analyzed cases of Hurthle cell tumors diagnosed and treated at a tertiary care center over a five-year period. Clinical, radiological, and histopathological data were meticulously collected and scrutinized. The study focused on examining demographic details, presenting symptoms, imaging features, cytological findings, surgical management, and postoperative outcomes of the patients.

RESULTS

A total of 32 cases of Hurthle cell tumors were identified during the study period. The majority of patients were female (84%), with a mean age of 49.6 years for Hurthle cell carcinoma. Thyroid enlargement and neck mass were the most common presenting complaints. Fine-needle aspiration cytology showed characteristic features suggestive of Hurthle cell tumors in 33% of cases. Total thyroidectomy remains the mainstay surgical approach. Histopathological evaluation confirmed 62.5% of cases as benign adenomas and 37.5% as malignant carcinomas. Among malignant cases, 67% showed capsular invasion and 33% demonstrated vascular invasion. Of the patients, 33.3% received adjuvant radiotherapy. The overall survival rate was 100%. In our study, we found that thyroid nodules larger than 3 cm demonstrated a higher propensity for Hurthle cell carcinoma.

CONCLUSION

Our findings support the multidisciplinary approach in managing Hurthle cell tumors, with a focus on tailored treatment plans for each patient based on individual characteristics. By recognizing the female predominance, assessing nodule size, and employing a combination of thyroidectomy and ablative therapy, clinicians can optimize patient care and contribute to better long-term prognosis and quality of life for those affected by Hurthle cell tumors. Continued research and collaborative efforts are necessary to advance our understanding and refine treatment strategies, paving the way for improved outcomes and enhanced patient management in the future.

Fine-needle aspiration biopsy of Hurthle cell lesions of the thyroid gland: A cytomorphologic study of 139 cases with statistical analysis

BACKGROUND

Lesions of the thyroid gland composed of Hurthle cells encompass pathologic entities ranging from hyperplastic nodules with Hurthle cell metaplasia to Hurthle cell carcinomas. The cytologic distinction between these entities can be diagnostically challenging. Many cytologic features of Hurthle cell lesions that distinguish neoplastic Hurthle cell lesions requiring surgery from those that are benign and nonneoplastic have been described, but with variable usefulness. This is due, in part, to the small numbers of cases examined in previous studies and the limited application of statistical analysis. A morphologic study was made of 139 Hurthle cell lesions of the thyroid gland and statistical analysis applied to identify a set of cytomorphologic features that distinguish benign Hurthle cell lesions (BHCL) from Hurthle cell neoplasms (HCN).

METHODS

Fine-needle aspiration biopsies (FNABs) of thyroid nodules with a predominant Hurthle cell component and corresponding histologic followup were included in the study. Cases were divided into BHCL and HCN groups on the basis of the histologic diagnosis. All cases were reviewed to assess the following 14 cytologic features: overall cellularity, cytoarchitecture, percentage of Hurthle cells, percentage of single cells, percentage of follicular cells observed as naked Hurthle cell nuclei, background colloid, chronic inflammation, cystic change, transgressing blood vessels (TBV), intracytoplasmic lumina, presence of multinucleated Hurthle cells, nuclear to cytoplasmic ratio, nuclear pleomorphism/atypia, and nucleolar prominence. The results were evaluated by using univariate and stepwise logistic regression (SLR) analysis; statistical significance was achieved at P-values < 0.05.

RESULTS

One hundred thirty-nine FNAB specimens, corresponding to 56 HCN and 83 BHCL, fulfilled the study criteria. Six of the 14 cytologic features evaluated were shown by univariate analysis to be statistically significant in predicting HCN: nonmacrofollicular architecture (P < 0.001), absence of background colloid (P < 0.001), absence of chronic inflammation (P < 0.001), presence of TBV (P < 0.001), > 90% Hurthle cells (P < 0.001), and >10% single Hurthle cells (P = 0.014). The first four of these features were also shown to be statistically significant in the SLR analysis (P = 0.005, 0.010, 0.016, and 0.045, respectively), and when all four of these features were present HCN was correctly identified 86% of the time.

CONCLUSIONS

In the current study of 139 FNAB specimens of thyroid Hurthle cell nodules, 14 cytologic features were examined and 6 were found to be statistically significant in identifying HCN. The following four features, when found in combination, were found to be highly predictive of HCN: nonmacrofollicular architecture, absence of colloid, absence of inflammation, and presence of TBV.

Computerized nuclear morphometry in thyroid follicular neoplasms

Differential diagnosis of follicular adenoma (FA) and follicular carcinoma (FC) of the thyroid can be challenging in the routine practice of surgical pathology because the diagnosis of FC is strictly defined and identification depends on the presence of invasion of the capsule or blood vessels. These features may be equivocally presented in the histological sections and interpreted subjectively by different pathologists, so an objective approach to solve this problem is essential. Computerized morphometry is a scientific tool to evaluate cellular changes and it can enhance the interpretation of morphological features by the transformation of pathological changes in cells to a qualitative form. The present study investigated the diagnostic role of objective computerized nuclear morphometry in follicular neoplasms. Thirty-six cases of thyroid FC and 36 cases of FA from patients who were matched by age and sex were studied. Four nuclear parameters were selected and analyzed: mean nuclear area, mean nuclear perimeter, largest to smallest diameter ratio of the nuclei, and coefficient of variation of the nuclear area. The results indicate that all the chosen nuclear variables were significantly correlated with the FA and FC studied. In conclusion, computerized nuclear morphometry can be considered a helpful ancillary tool for differential diagnosis of FA and FC.

Contribution of morphometry in the differential diagnosis of fine-needle thyroid aspirates

BACKGROUND

Cytologic discrimination of cellular nodules, follicular adenoma, and follicular carcinoma in the thyroid is problematic. Methods are needed to achieve a reliable diagnosis. Some sophisticated tools, such as microarrays, offer great potential but lack accompanying morphologic information.

METHODS

One hundred twelve samples obtained from patients with lesions histopathologically diagnosed as nodular goiter, follicular adenoma, follicular carcinoma, and papillary carcinoma were used. Eight geometric features, such as nuclear area and circular form factor, were measured. The dataset was divided into six overlapping groups to represent the frequently encountered situations in routine practice. Multivariate analysis of variance, Tukey's honestly significant differences test, and discriminant analysis were performed. Statistical analysis was carried out with two conceptually different approaches. In the first, data from all measured nuclei were used. In the second, a subset of data representing the most extreme values of variables was extracted from the entire dataset to simulate the "selection procedure" performed during conventional morphologic examination.

RESULTS

When the selected dataset instead of data from all measured nuclei was used, the correct classification rates in discriminant analysis improved considerably.

CONCLUSIONS

Morphologic examination is based primarily on selection. Using data obtained from all of the cells in morphometry may cause a dilution effect in diagnostically important features. Morphometric studies may also be planned with a proper selection "bias." This may be particularly helpful when isolated abnormal cells carry most of the diagnostic information.

Thyroid carcinoma diagnosis based on a set of karyometric parameters of follicular cells

BACKGROUND

In the works of various authors, performed with the help of morphometry, an assessment of cell changes was carried out, as a rule, by one sign of their atypia (e.g. area of cell nuclei). Moreover, the selective analysis of morphometric data for certain nosologic forms was performed. Such an approach allowed researchers to develop only additional diagnostic criteria of thyroid carcinoma. At the same time, the use of a set of quantitative signs of cell atypia as a criterion for tumor malignancy made it possible to improve oncologic diagnosis. In this study, which is a first step in the development of a quantitative approach to thyroid carcinoma diagnosis, a system of karyometric parameters was developed with the help of morphometry of cytologic material of patients with major nosologic forms of thyroid pathology (papillary and follicular carcinoma, follicular adenoma, autoimmune thyroiditis, and nodular colloid and diffuse toxic goiter). The significance of each parameter in thyroid carcinoma diagnosis was evaluated.

METHODS

Thyroid cells of autopsy, operative, and aspiration biopsy material were the object of the study. One hundred fifty-two preparations with histologically verified diagnosis were studied. Light morphometry was performed with the help of a semiautomatic computer analyzer of images. One hundred fifty thyroid nuclei were assessed in each preparation.

RESULTS

Among many karyometric parameters, six were selected: mean area of thyrocyte nuclei, ratio of frequencies, and number of classes on histograms of distribution of their area, coefficient and a free term of the regression equation to a scattered diagram of perimeter and nuclear area, and the discriminant index. Boundary values of these parameters between the malignant and benign pathology were united into an expert system for thyroid carcinoma diagnosis. Clinical trials of the system were performed. On the basis of the obtained results, the informativity (accuracy, sensitivity, specificity) of its karyometric parameters was assessed. The formula for calculation of the weighting coefficient for each parameter was derived, the diagnostic index being determined by the sum of their values.

CONCLUSIONS

An expert system was created based on a set of karyometric parameters reflecting the regularities of pathologic changes in thyrocyte nuclei with malignant and benign pathology. The informativity and weighting coefficients included into the system of parameters have been assessed, which made it possible to perform the probabilistic diagnosis of thyroid carcinoma.

Morphology of FRTL-5 cell colonies in a semi-solid medium

For the first time, 3, 7 and 10 days growth of normal thyroid follicular FRTL-5 cell colonies in a semi-solid medium of 0.6% methocel over 1% agar base was morphometrically analyzed. It was found that the areas of FRTL-5 colonies as well as their perimeters and maximum diameters increased, while according to their form factors the FRTL-5 colonies were regular in shape. After 10 days in a semi-solid medium, 83% of the FRTL-5 colonies had maximum diameters greater than 50 microm. It is obvious that after long culturing of FRTL-5 cells under the influence of the pituitary thyroid-stimulating hormone (TSH) these cells are not uniform anymore and that they grow in a semi-solid medium.

Hurthle cell adenoma of the mediastinum: intraoperative cytology and differential diagnosis with correlative gross, histology, and ancillary studies

A 66-year-old man was found to have a 7.5 cm mediastinal mass detected on routine chest X-rays as part of his preoperative work up for an inguinal hernia repair. An orthotopic (normally located) nongoitrous thyroid gland without evidence of connection to the mediastinal mass was also identified. The clinical differential diagnoses included lymphoma, thymoma, and germ cell tumor. Fine-needle aspiration (FNA) biopsy smears and touch imprints of the mediastinal mass showed a loosely cohesive, highly cellular population of relatively uniform cells with abundant granular cytoplasm, low nuclear to cytoplasmic (N/C) ratios, and prominent nucleoli consistent with a Hurthle cell (HC) neoplasm. Subsequently, the diagnosis of HC adenoma was confirmed on the surgically excised mediastinal mass. To the best of our knowledge, the surgical pathology and cytologic features of an HC adenoma of the mediastinum have not been reported in the literature. The gross, histologic, immunohistochemical, and electron microscopic (EM) findings, in addition to the cytologic features, are presented along with a differential diagnosis of this mediastinal neoplasm.

Diagnostic significance of papillary structures and intranuclear inclusions in Hurthle-cell neoplasms of the thyroid

Papillary structures and intranuclear inclusions, features which are not ordinarily associated with Hurthle-cell lesions, are occasionally noted within Hurthle-cell-rich aspirates. The diagnostic significance of these features in this setting, if any, is unknown. The purpose of this study was to determine whether these features are diagnostically useful. Specifically, since fine-needle aspiration cytology cannot distinguish between Hurthle-cell adenoma and carcinoma, we wanted to know whether the presence of either feature might aid in preoperatively assessing the likelihood of carcinoma vs. adenoma. We identified 12 cases in which a diagnosis of Hurthle-cell lesion was made by thyroid fine-needle aspiration biopsy. All cases had subsequent surgery. For every case, all cytology slides were reviewed for the presence or absence of papillary structures and intranuclear inclusions, after which the findings were correlated with the final surgical pathological diagnosis. Seven of the 12 cases had identifiable papillary structures, ranging from cases where papillary structures comprised the predominant architectural pattern to cases where rare papillary structures were found amidst a predominance of sheets and single Hurthle cells. Four of the 12 cases had intranuclear inclusions. In all cases, intranuclear inclusions were uncommon. Of 6 cases that proved to be Hurthle-cell carcinoma, 5 had papillary structures on the antecedent fine-needle aspirate cytology, and 2 had intranuclear inclusions. Of 6 cases that proved to be Hurthle-cell adenoma, 2 had papillary structures, and 2 had intranuclear inclusions. Papillary structures had a sensitivity of 83% for the presence of carcinoma, a specificity of 66%, a positive predictive value of 71%, and a negative predictive value of 80% (P = 0.2). Intranuclear inclusions had a sensitivity of 33%, a specificity of 66%, and positive and negative predictive values of 50%. Papillary structures are more common in Hurthle-cell aspirates than previously recognized. Their presence is not diagnostic of carcinoma, but neither does their absence rule out carcinoma. However, when found, the likelihood of an ultimate diagnosis of Hurthle-cell carcinoma is increased. On the other hand, intranuclear inclusions, when rare, appear to have no diagnostic value.