Cytomorphologic Diversity of Papillary Thyroid Carcinoma

Utility of solid area diameter in management of cystic papillary thyroid carcinoma

Papillary thyroid carcinoma (PTC) with marked cystic formation (CPTC) is not a subtype of PTC, and its clinical characteristics have not been fully investigated. This study aimed to clarify the clinical and pathological characteristics of CPTC and propose important indicators for its clinical management. Thirty-three CPTC nodules with cystic areas occupying >50% of their volume were examined. Two matched controls (MCs) were prepared, one with tumor diameter matched for whole tumor diameter (WTD) of CPTCs and the other with tumor diameter matched for solid area diameter (SAD) of CPTCs. The mean age of patients with CPTC was 55.2 years significantly older than that in SAD-MCs. Of the CPTCs, 69.7% were classified as highly suspicious by ultrasonography, and the prevalence was lower than that in WTD-MCs (88.9%) and SAD-MCs (91.5%). Total thyroidectomy was performed in 69.7% of CPTC cases, which was significantly less frequent than that in WDT-MCs (91.7%) and similar to that in SAD-MCs (76.1%). Histologically, CPTCs exhibited two characteristic findings: invasion from the solid area into the surrounding normal thyroid tissue and granulation tissue around the cystic wall. The frequencies of the cases with pathological lateral node metastasis, extrathyroidal extension, and Ki-67 labeling index ≥5% in CPTCs were significantly lower than those in WTD-MCs and relatively similar to those in SAD-MCs. In the surgical strategy and prognosis of CPTC, the evaluation of tumor size should be based on SAD rather than on WTD. We advocate measuring not only WTD but also SAD in CPTC.

Warthin-like papillary carcinoma thyroid

Solitary thyroid nodule should raise a suspicion of malignancy, which is very common in middle-aged females. Papillary carcinoma thyroid is the most common thyroid malignancy. Warthin-like papillary carcinoma is one of its rare variants. It has a frequent association with Hashimoto's thyroiditis. Here, we report a case of 43-year-old female who presented with swelling in the anterior aspect of neck for 1 month. Fine-needle aspiration cytology features were suggestive of papillary carcinoma thyroid and biopsy confirmed the diagnosis of Warthin-like papillary carcinoma thyroid. This variant is of great clinical and prognostic significance as it carries an excellent prognosis.

Cytomorphologic features as predictors of aggressiveness in patients with pT1 papillary thyroid carcinoma: a retrospective study of associations with clinicopathological parameters in 226 fine-needle aspirates

Background

Distinguishing aggressive pT1 papillary thyroid carcinomas (PTCs) from indolent PTCs before or during surgery is important. To the best of our knowledge, few reports in the literature have examined the value of the cytomorphologic features of PTC as predictors of aggressiveness.

Methods

This retrospective study included 226 pT1 PTC patients who underwent preoperative fine-needle aspiration cytology (FNAC) and surgery at Peking University Cancer Hospital between January 2018 and December 2019. Data on the clinical characteristics and pathological results were obtained from the electronic medical record database. All FNAC smears were blindly reviewed by two independent cytopathologists, and the associations between nine cytomorphologic features (lymphocytes, multinucleated giant cells, cellularity, cellular adhesiveness, nuclear size, nuclear pleomorphism, nuclear membrane regularity, intranuclear pseudoinclusions and the amount of cytoplasm) and clinicopathological parameters were statistically analyzed.

Results

Univariate analysis showed that cellularity, intranuclear pseudoinclusions, cellular adhesiveness, nuclear size, and nuclear pleomorphism were strong predictors of some clinicopathological parameters such as extracapsular invasion (ECI) and lymph node metastasis (LNM). Multivariate analysis confirmed that cellular adhesiveness was a strong independent predictor of ECI (P=0.001) and LNM (P<0.001), and the amount of cytoplasm can also predict LNM (P=0.024).

Conclusions

Cytomorphologic features including cellular adhesiveness and the amount of cytoplasm in preoperative FNAC smears could be a valuable tool for predicting ECI or LNM and may be predictors of aggressiveness in patients with pT1 PTC.

[Limitation of possibilities of cytological diagnosis of papillary thyroid cancer at the pre-surgery stage]

AIM OF STUDY

A comparison of papillary cancer variants diagnosed on the basis of cytological findings of pre-surgery puncture biopsies with a histological variant of papillary cancer.

MATERIALS AND METHODS

The findings of two experts specializing in cytological diagnostics of thyroid nodules that diagnosed a possible variant of papillary cancer were compared with histological findings based on the study of material from surgically removed neoplasms.

RESULTS

It was shown that the cytological examination at the pre-surgery stage has significant limitations in diagnosing the histological variant of the tumor, despite high sensitivity of method in diagnosing papillary cancer in general. The variability of results of the cytological determination of papillary cancer variant between the two experts was not so significant, it concerned small fluctuations in the frequency of the diagnosing og normal, follicular, cystic and Uortino-like variants. Based on the data of cytological method, it is not possible to establish the encapsulated variant and papillary microcarcinoma; there are limitations in the diagnosis of follicular and high tumor cell variants.

CONCLUSIONS

Currently, the advisability of the recommendation to determine the variant of papillary cancer using the cytological method is questionable. However, this does not mean that it is necessary to stop the search for reliable cellular and molecular genetic characteristics of clinically aggressive variants of papillary cancer.

Cribriform-morular variant of papillary thyroid carcinoma and its association with familial adenomatous polyposis

The cribriform-morular variant of papillary thyroid carcinoma (CMV-PTC) is an uncommon variant of papillary thyroid carcinoma. CMV-PTC can be associated with familial adenomatous polyposis (FAP), an autosomal-dominant polyposis syndrome caused by a mutation in the APC gene that leads to a disruption of the Wnt/beta-catenin pathway. Understanding the relation between CMV-PTC and FAP is a diagnostic tool for both pathologists and clinicians, because FAP has several implications for patients and their families.

Cytologic features of aggressive variants of follicular-derived thyroid carcinoma

Certain carcinomas of the thyroid gland behave aggressively resulting in increased patient morbidity and poor patient prognosis. The diagnosis of these aggressive thyroid cancer subtypes is sometimes challenging and subject to increased interobserver variability. This review deals with the cytological features of such tumors including aggressive variants of papillary thyroid carcinoma, poorly differentiated thyroid carcinoma, and anaplastic thyroid carcinoma. These malignancies fall into 2 groups based on their cytomorphology: those that exhibit distinct microscopic features (eg, nuclear findings typical of classical papillary thyroid carcinoma or marked anaplasia) and those that present with more subtle cytologic features (eg, nuclear pseudostratification, "soap bubble" nuclei, supranuclear or subnuclear cytoplasmic vacuoles, rosette-like structures, hobnail cells). We review the literature regarding these aggressive thyroid cancers and highlight important phenotypic characteristics that can be useful for their diagnosis based on fine needle aspiration.

Diagnostic clues indicating tall cell variants of papillary thyroid carcinoma in fine needle aspiration

BACKGROUND

The definition of tall cell variant of papillary thyroid carcinoma (TCV-PTC) depends on the articles, and the defined cytological findings characteristic of TCV-PTC have not yet been fully analyzed. This study aimed to establish the cytological characteristics of TCV-PTC.

METHODS

We retrospectively analyzed the smears of 19 TCV-PTC and 50 conventional PTC (C-PTC) cases.

RESULTS

Palisaded pattern with the nuclei locating at the base of tall columnar carcinoma cells was seen in 94.7% of TCV-PTCs, and the incidence was significantly higher than that of C-PTCs (P < .0001). The palisaded pattern tended to appear at the periphery of the cell clusters. Isolated tall columnar carcinoma cells were present in 89.5% of TCV-PTCs. The incidence was significantly higher than that of C-PTC (P = .0001). Tombstone appearance was identified in 78.9% of TCV-PTCs, but not in C-PTCs. Spindle-like carcinoma cells with tapering cytoplasmic end appeared in 68.4% and 12.0% of TCV-PTC and C-PTC, respectively (P < .0001). The cytoplasm of TCV-PTC was densely stained and its cell border was distinct. Cytoplasmic elongation toward an outside of the cell clusters was observed in 89.5% of TCV-PTCs.

CONCLUSION

It is the most important to identify the presence of the tall columnar carcinoma cells on the cytological preparations, in order to distinguish TCV-PTC from C-PTC. We propose five cytological findings indicating TCV-PTC, (1) palisaded pattern, (2) tall columnar cells with the heights of at least three times their widths, (3) tombstone appearance, (4) spindle-like carcinoma cells, and (5) cytoplasmic elongation.

Distinguishing non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) from classic and invasive follicular-variant papillary thyroid carcinomas based on cytologic features

INTRODUCTION

An international panel recently recommended reclassification of non-invasive follicular variant of papillary thyroid carcinoma (PTC) to non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP). NIFTPs have little or no risk of recurrence and can be treated with lobectomy alone. Preoperative distinction of NIFTP from PTC will help avoid overtreatment.

MATERIALS AND METHODS

All thyroid tumors with a histologic diagnosis of PTC and preceding diagnostic cytology (n = 299) over a 5-year period were identified. Cases meeting criteria for NIFTP were reclassified as such. All NIFTP cases with available cytology (n = 6) and a similar number of randomly selected invasive follicular variant of papillary thyroid carcinoma (IFVPTC; n = 9) and classic PTC (cPTC, n = 11) were evaluated for 18 cytologic features.

RESULTS

A total of 35 (12%) lesions were reclassified as NIFTP, 194 (65%) were cPTC, and 70 (23%) were IFVPTC. The NIFTPs had a preceding cytologic interpretation of benign (31%), atypia of undetermined significance (34%), follicular neoplasm (9%), suspicious for malignancy (12%), or malignant (14%). Cytologically, NIFTP was distinguished from cPTC by absence of any architectural features in all 6 cases, and by absence of pseudoinclusions (P < 0.001) and multinucleated giant cells (P = 0.027) in nearly all. Nuclear pseudoinclusions (P = 0.001), marginal micronucleoli (P = 0.018), irregular branching sheets (P = 0.025), and linear arrangement (P = 0.025) favored IFVPTC over NIFTP.

CONCLUSIONS

NIFTPs were originally assigned to a variety of cytologic categories. There are several cytologic differences between NIFTP and cPTC or IFVPTC. Our findings support restricting the definitive diagnosis of PTC to cases with architectural features of PTC and/or intranuclear pseudoinclusions.

Cribriform-morular variant of thyroid carcinoma: a neoplasm with distinctive phenotype associated with the activation of the WNT/β-catenin pathway

Cribriform-morular variant of thyroid carcinoma is classically associated with familial adenomatous polyposis but, it can also occur as a sporadic neoplasm. This neoplasm is much more frequently observed in women than in men (ratio of 61:1). In familial adenomatous polyposis patients, tumors are generally multifocal and/or bilateral (multinodular appearance), whereas in the sporadic cases tumors tend to occur as single nodules. The tumors are well delimited, and characteristically show a blending of follicular, cribriform, papillary, trabecular, solid, and morular patterns. Neoplastic cells are tall or cuboidal with the occasional nuclear features of classic papillary thyroid carcinoma. The morules include cells with peculiar nuclear clearing and show positivity for CDX2 and CD10. Angioinvasion and capsular invasion have been described in about 30 and 40% of cases, respectively, with lymph node metastases in less than 10% of patients and distant metastases in 6%. Although this tumor has good prognosis, neuroendocrine and/or poor differentiation have been associated with aggressive behavior. Tumor cells can be focally positive or negative for thyroglobulin, but are always positive for TTF-1, estrogen and progesterone receptors, and negative for calcitonin and cytokeratin 20. Nuclear and cytoplasmic staining for β-catenin is the hallmark of this tumor type; this feature plays a role in fine needle aspiration biopsy. Cribriform-morular variant of thyroid carcinoma has a peculiar endodermal (intestinal-like) type phenotype, activation of the WNT/β-catenin signaling pathway, and belongs to the non-BRAF-non-RAS subtype of the molecular classification of thyroid tumors. Elevated expression of estrogen and progesterone receptors and activation of the WNT/β-catenin pathway may prove useful as putative therapeutic targets in cases that do not respond to conventional therapy. Clinicians should be alerted to the possibility of familial adenomatous polyposis when a diagnosis of cribriform-morular variant of thyroid carcinoma is made. Instead of being considered as a variant of papillary thyroid carcinoma its designation as cribriform-morular thyroid carcinoma seems more appropriate.