3-D analysis of vascular and capsular invasion in thyroid follicular carcinoma

Prognostic impact of vascular invasion in differentiated thyroid carcinoma: a systematic review and meta-analysis

BACKGROUND

The role of vascular invasion (VI) as a prognostic marker in thyroid cancer is continuously debated among investigators. In this systematic review and meta-analysis, we aimed to investigate the association of VI with tumor recurrence and patient mortality in differentiated thyroid cancers (DTCs).

METHODS

We searched five electronic databases for cases of DTC matching our criteria. Data of tumor persistence, locoregional recurrence (LRR), distant recurrence (DR) and overall recurrence/persistence (RP) were extracted and pooled into odds ratios (OR) and corresponding 95% confidence intervals (CIs) using random effect model. Pooled hazard ratio (HR) for disease-specific survival (DSS) was calculated using random effect model weighted by inverse variance method. Publication bias was examined by using Egger's test and funnel plot.

RESULTS

From 1650 studies, we included 26 studies comprising 11 961 DTCs for meta-analyses. In DTC patients, we found significant associations of VI with tumor persistence (OR = 2.75; 95% CI = 1.46-5.18), LRR (OR = 4.44; 95% CI = 2.94-6.71), DR (OR = 5.08; 95% CI = 2.95-8.75), overall RP (OR = 3.53; 95% CI = 2.09-5.96) and worse DSS (HR = 2.47; 95% CI = 1.45-4.21). Our results also demonstrated that the presence of extensive VI is associated with a significantly higher risk for DR in follicular thyroid carcinomas as compared with focal VI.

CONCLUSION

Our study demonstrated a significant impact of VI on tumor recurrence and patient survival in DTC patients. The presence and extent of VI should be considered an adverse prognostic factor in DTCs.

Unusual thyroid tumors: a review of pathologic and molecular diagnosis

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

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.

Histological patterns of locoregional recurrence in Hürthle cell carcinoma of the thyroid gland

BACKGROUND

Hürthle cell carcinoma (HCC) is regarded as an aggressive variant of follicular thyroid carcinoma based in part on its propensity to metastasize regionally and recur locally. The current treatment recommendation of formal regional lymph node dissection is largely based on the presumption of lymphatic dissemination to cervical lymph nodes as the main mechanism of regional spread. The purpose of this study was to better define the distribution of locoregional recurrence in HCC, and specifically to differentiate soft-tissue implants from true nodal metastases.

METHODS

The surgical pathology files of The Johns Hopkins Hospital were searched for cases of HCC with locoregional recurrences. The slides were reviewed to assess the histologic patterns of tumor spread, including the presence or absence of lymph node metastasis. Elastic staining was used to confirm vessel invasion.

RESULTS

Twenty-four cases from 19 patients were identified. Thirteen were men, and the patients ranged in age from 35 to 83 years (mean 66). All had total or near-total thyroidectomies, and 16 received postoperative radioactive iodine. The time from primary diagnosis to first recurrence ranged from 0 to 12 years (mean 5 years). The locoregional disease involved the lateral neck (n=16), central neck (n=18), and larynx/trachea (n=4). In all 24 cases, the dominant tumor nodule was present as a rounded nodule of carcinoma within the soft tissues and unassociated with lymphoid tissue. Of 22 cases evaluated by elastic staining, 13 had tumor nodules within veins. True lymph node metastases were present in only six (25%) cases, and in all but one case, the lymph node metastases were <0.5 cm.

CONCLUSIONS

When HCC spreads in the neck, it usually does so as soft-tissue implants likely resulting from spread within venous channels. True lymph node metastases are not a major source of nodular recurrences in the neck. Resolving the pattern of tumor spread could help guide and refine the management of locoregional recurrence for patients with HCC.

Pathological definition and clinical significance of vascular invasion in thyroid carcinomas of follicular epithelial derivation

There are many controversies involving the diagnostic criteria and treatment of well-differentiated thyroid carcinoma. Vascular invasion has been identified as an important and independent prognosticator in many cancers. The majority of pathologists recognize the importance of vascular invasion as a diagnostic marker of malignancy in follicular lesions of thyroid; however, several reports have suggested that angioinvasion is not a predictor of bad prognosis in thyroid carcinomas. We suggest that the criteria for diagnosing angioinvasion in thyroid carcinomas as well as in other endocrine tumors are inconsistent and the controversy may be attributed to application of inappropriate criteria. We carried out a study of a potential cause of artefactual vascular invasion in a series of autopsy thyroids and established the morphology of mimics of angioinvasion. We then reviewed retrospectively the clinicopathological features of a series of 4000 thyroid carcinomas of follicular epithelial derivation to identify the features and significance of the most rigid criteria of vascular invasion: tumor cells invading through a vessel wall and thrombus adherent to intravascular tumor. These features were identified in 118 (3%) lesions. Follow-up information was available for 98 patients. Of these, 35% developed distant metastases. When using the rigid criteria, ∼1/3 of angioinvasive well-differentiated thyroid carcinomas and 1/2 of angioinvasive poorly differentiated thyroid carcinomas developed distant metastases at a mean 5.3 years of follow-up. Our results indicate that the application of rigid criteria for vascular invasion provide a clinically relevant prediction of distant metastasis in patients with thyroid carcinomas, especially in well-differentiated thyroid carcinomas.

Vascular and Capsular Pseudoinvasion in Thyroid Neoplasms

The diagnosis of follicular carcinoma of the thyroid requires the identification of capsular and/or vascular invasion, with the exception of distant metastases. However, several artifacts may mimic both vascular and capsular invasion. This article presents two cases of pseudo invasion in encapsulated follicular neoplasms. Their differentiation from true vascular and capsular invasion is discussed and the criteria for true invasion are reviewed.

Significance of Tumor Capsular Invasion in Well-Differentiated Thyroid Carcinomas

This study examines the influence of tumor capsular invasion on the biological behavior of papillary (PTC) and follicular thyroid carcinoma (FTC) and the prognosis of surgically treated patients. This retrospective cohort study included 350 cases of PTC or FTC from a university teaching hospital. Patient charts were randomly selected and reviewed. The study population was divided into PTC and FTC groups. Each group was subdivided into CI+ (with tumor capsular invasion) and CI- subgroups (without tumor capsule or without capsular invasion). The long-term prognosis was assessed using the American Joint Committee on Cancer pTNM staging and the prognostic index was elaborated by the European Organization for Research and Treatment of Cancer. There were 284 women and 66 men (ages 19–89 years, mean of 44) with an incidence of 53.1 per cent for CI+ tumors. There were no significant differences between the PTC subgroups regarding the short-term clinical outcome and the long-term prognosis. Although patients with CI+ FTC showed lower incidence of lymph node metastasis than patients with CI- FTC, the FTC subgroups were comparable regarding the short-term clinical outcome and the long-term prognosis. Our results suggest that presence of tumor capsular invasion does not adversely influence biological behavior or survival of PTC or FTC. Moreover, the presence of tumor capsular invasion appears to not have significance for the long-term prognosis of patients with PTC or FTC.

Tissue arrays as fiducial markers for section alignment in 3-D reconstruction technology

Combination of conventional histology and the three-dimensional spatial view of tissue structures offers new prospects for understanding and diagnosing nature and development of human diseases. The essential technical problem related to three-dimensional reconstruction in histopathology is represented by the correct alignment of serial sections. During the past years several methods have been proposed but failed to become popular because of their limits in terms of time consume and restricted applicability. We aimed to overcome this problem by applying the technology of Tissue Array, thus by positioning adequate fiducial markers from specific "donor" blocks into the "recipient" paraffin block of interest. Digitized pictures of serially cut sections were aligned according to the tissue markers embedded by Tissue Array, and then processed with specific softwares for three-dimensional reconstruction. Thirteen models, including fetal hearts, breast and thyroid carcinomas, were elaborated. We found the procedure to be easy, fast and reproducible. Moreover, by selectively embedding the fiducial markers according to specific angles, the Tissue Arrays can be exploited in order to establish the distance between sections. This original methodology of incorporating Tissue Arrays into paraffin blocks as fiducial markers for three-dimensional reconstruction has a potential impact on histology for research purposes and diagnostic applications.

Three-dimensional reconstruction of basal cell carcinomas

BACKGROUND

Basal cell carcinoma (BCC) is the most common type of skin cancer. One of the main problems with BCC is the risk of local recurrence of the tumor after treatment. This is mainly due to its irregular outgrowths, which cannot be detected clinically.

OBJECTIVE

To better understand the tumor morphology and growth pattern of BCC, we tried to develop a method that provides a precise three-dimensional model of the tumor.

METHODS

Because Mohs surgery provides the best overview of the tumor and the tumor margins (both lateral and in depth), the reconstruction was based on slides from Mohs surgery. After digitization and processing of the slides, the tumor was then surrounded by a Mohs surgeon on a computer screen. These selections (lines) were used for a three-dimensional reconstruction of the tumor using MedSurf3D software.

RESULTS

This method allows three-dimensional reconstruction of any given BCC. The MedSurf3D software enables visualization of a three-dimensional model of the tissue, which is removed during the surgical procedure.

CONCLUSIONS

Three-dimensional reconstruction is a fascinating tool that might improve our understanding of the behavior, growth pattern, and tumor morphology of BCCs. This technique might also be useful in other fields of cutaneous oncology, such as the calculation of the tumor volume of melanomas.

Clinicopathologic significance of histologic vascular invasion in papillary and follicular thyroid carcinomas1 1No competing interests declared

BACKGROUND

The association of angioinvasion with tumor aggressiveness in follicular and papillary thyroid carcinoma remains unclear. This study addresses this problem focusing on clinicopathologic relevance of angioinvasion in the treatment of papillary thyroid carcinoma and follicular thyroid carcinoma.

METHODS

From a university hospital database, 358 patients with papillary thyroid carcinoma or follicular thyroid carcinoma were randomly selected. Their charts were retrospectively analyzed and divided into papillary thyroid carcinoma and follicular thyroid carcinoma groups. Each group was subdivided into angioinvasive and nonangioinvasive tumor subgroups. All data were analyzed using Student's t-test, Mann-Whitney rank sum test, chi-square test, and Fisher's exact test.

RESULTS

There were 289 women and 69 men, ages 18 to 89 years. Papillary thyroid carcinoma (86%) was more frequent than follicular thyroid carcinoma. Most patients had nonangioinvasive tumor (90.2%). After a mean followup of 43.6 months, there were no significant differences between papillary thyroid carcinoma subgroups for local recurrence (p = 0.69), persistent elevated serum thyroglobulin (p = 0.568), and distant metastasis rates (p = 0.422). No death related to the cancer was observed in both papillary thyroid carcinoma subgroups (p = 1), except for one death resulting from a concomitant nasopharyngeal cancer. The longterm prognosis was less favorable for angioinvasive papillary thyroid carcinoma based on AJCC (American Joint Committee on Cancer staging), AMES (age, distant metastasis, tumor extent, and size), and MACIS (distant metastasis, age, completeness of primary tumor resection, local invasion, and tumor size), but the angioinvasive papillary thyroid carcinoma were larger than nonangioinvasive papillary thyroid carcinomas. The short-term clinical outcomes in both follicular thyroid carcinoma, after a mean followup of 72.3 months, were comparable in terms of local recurrence (p = 0.34), persistent elevated serum thyroglobulin (p = 1), and distant metastasis (p = 0.597). There was no death related to cancer in both follicular thyroid carcinoma subgroups (p = 1). There were no significant differences between both follicular thyroid carcinoma subgroups for longterm prognosis.

CONCLUSIONS

Our results indicate that angioinvasion does not adversely influence short-term outcomes or longterm prognosis in follicular thyroid carcinoma and short-term outcomes in papillary thyroid carcinoma. Angioinvasion is a postoperative pathologic finding that does not justify an ominous prognosis or drastic therapeutic measures.

A novel microdissection and genotyping of follicular-derived thyroid tumors to predict aggressiveness

Distinguishing thyroid follicular adenoma from minimally invasive or encapsulated angioinvasive carcinoma can be diagnostically challenging. In some cases, tumors are distorted, fragmented, or stripped of their capsule, and a definitive diagnosis becomes nearly impossible. In other cases, the foci of capsular and/or vascular invasion are subtle, thus making the diagnosis of carcinoma difficult. We developed a microdissection genotyping assay for assessing a panel of tumor-suppressor genes for loss of heterozygosity mutations. The frequency of allelic loss (FAL) in follicular-derived neoplasms correlates with the histologic aggressiveness of the tumor. Furthermore, we calculated the amount of genetic heterogeneity within each tumor, as a second important measure of a tumor's ability for clonal expansion and a surrogate marker for its malignant potential. The follicular adenomas had a low FAL (average 9%) and low intratumoral heterogeneity (5% variability). The minimally invasive and encapsulated angioinvasive carcinomas had an intermediate FAL (average 30%) and intermediate intratumoral heterogeneity (10% variability). The widely invasive carcinomas had a high FAL (average 53%) and high intratumoral heterogeneity (24% variability). Although a larger retrospective study is needed to correlate genotyping studies with patient outcome and prognosis, our results indicate that performing a mutational genotyping assay can stratify tumors into the histologically well-defined categories of adenomas, minimally invasive/angioinvasive carcinomas, and widely invasive follicular carcinomas.