Tall Cell Variant of Papillary Thyroid Carcinoma without Extrathyroid Extension: Biologic Behavior and Clinical Implications
Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, New York, United States Thyroid
(Impact Factor: 4.49).
07/2007; 17(7):655-61. DOI: 10.1089/thy.2007.0061
The tall cell variant (TCV) is a histologic subtype of papillary thyroid carcinoma (PTC) that is more aggressive than "classical" PTC. Most authors believe that TCV's worse prognosis is related to older age at presentation, larger tumor size, and high frequency of extrathyroid tumor extension (ETE). To assess the biologic and clinical behavior of TCV without ETE, we performed a detailed comparative clinicopathologic analysis of classical PTC and TCV without ETE.
TCV was defined as a PTC harboring >50% tall cells, while classical PTC was restricted to those tumors containing >1% papillae and <30% tall cells. Microscopic analysis and chart review identified 62 cases of TCV and 83 classical PTC without ETE. These patients were analyzed for various pathologic, imaging, and clinical parameters including outcome.
There was no statistical difference between TCV and classical PTC in relation to age, gender, tumor size, risk stratification, type of therapy, and length of follow-up. TCV displayed more invasion of the tumor capsule and more often infiltrated into the thyroid capsule (p = 0.047 and 0.0004, respectively). Among patients with microscopically assessable regional lymph node (LN), 33 of 49 (67.3%) patients with TCV had LN metastasis at presentation, while only 24 of 60 (40%) classical PTC had positive nodes (p = 0.004). In multivariate analysis, histologic subtype (TCV vs. classical PTC) was the only independent factor associated with LN metastases (p = 0.007). In patients with adequate follow-up, 4 of 62 (6.5%) classical PTC and 7 of the 47 (14.9%) TCV had thyroid cancer recurrence (p = 0.202). TCV recurred at a distant site (3 of 47, 6.4%) while none of the 62 classical PTC developed distant metastases (p = 0.077).
TCV without ETE is biologically a more aggressive tumor than classical PTC without ETE independent of age, gender, and tumor size.
Available from: Ja Seong Bae
- "Some studies suggest that TCV PTC is still under-diagnosed worldwide.3,4,5,9,10 In fact, 1% to 13% of tumors originally diagnosed as classic PTC can be reclassified as TCV by thyroid expertise.11,12 TCVPTC was originally described by Hawk and Hazard9 in 1976 as a distinctive subtype of PTC. "
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The tall cell variant of papillary thyroid carcinoma (TCVPTC) is more aggressive than classic papillary thyroid carcinoma (PTC), but the percentage of tall cells needed to diagnose TCVPTC remains controversial. In addition, little is known about the clinicopathologic features of classic PTC with tall cell features (TCF).
We retrospectively selected and reviewed the clinicopathologic features and presence of the BRAF mutation in 203 cases of classic PTC, 149 cases of classic PTC with TCF, and 95 cases of TCVPTCs, which were defined as PTCs having <10%, 10-50%, and ≥50% tall cells, respectively.
TCVPTCs and classic PTCs with TCF did not vary significantly in clinicopathologic characteristics such as pathologic (p) T stage, extrathyroidal extension, pN stage, lateral lymph node metastasis, or BRAF mutations; however, these features differed significantly in TCVPTCs and classic PTCs with TCF in comparison to classic PTCs. Similar results were obtained in a subanalysis of patients with microcarcinomas (≤1.0 cm in size).
Classic PTCs with TCF showed a similar BRAF mutation rate and clinicopathologic features to TCVPTCs, but more aggressive characteristics than classic PTCs.
Available from: Michael P Lavalley
- "Unlike the usually good prognosis of usual variant papillary thyroid cancer (UV), TCV histology is generally reported as an independently poor prognostic factor      . "
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ABSTRACT: Objective. To evaluate the prognosis of tall cell variant (TCV) compared to usual variant (UV) papillary thyroid cancer by comparing disease-related mortality and recurrence data from published studies. Methods. Ovid MEDLINE keyword search using "tall cell variant papillary thyroid cancer" was used to identify studies published in English that calculated disease-related mortality and recurrence rates for both TCV and UV. Results. A total of 131 cases of tall cell variant papillary thyroid cancer were reviewed. The combined odds ratio of recurrence for TCV compared to UV is 4.50 with a 95% confidence interval from 2.90 to 6.99. For disease-related mortality, the combined odds ratio for TCV was compared to UV of 14.28 with a 95% confidence interval from 8.01 to 25.46. Conclusion. Currently published data suggests that TCV is a negative prognostic indicator in papillary thyroid cancer and requires aggressive therapy. This meta-analysis provides the largest prognostic data series on TCV in the literature and clearly identifies the need for accurate pathological identification of TCV and its further study as an independent prognostic factor.
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ABSTRACT: Thyroid cancer is the most common endocrine malignancy and its incidence is increasing [1, 2]. Differentiated thyroid cancer
consists of papillary, follicular, and Hurthle cell histological types. Although it typically has a good prognosis due to
its long, indolent, and well-tolerated natural history, lifelong follow-up is recommended as late recurrences may occur after
surgery. Advances in diagnostic modalities and pathologic analysis continue to evolve. High-resolution ultrasound plays an
increasingly important role in the management of thyroid cancer, including diagnosis of malignancy, preoperative lymphatic
mapping and postoperative surveillance. Surgery remains the mainstay of therapy; however, thyroid suppression and radioactive
iodine ablation also contribute to the treatment. The first section of this chapter contains an overview of the clinical characteristics
of well-differentiated thyroid cancer including risk factors, symptoms, diagnosis, histologic types, management and follow-up
strategies. The second part will provide a more detailed evaluation of the effects of the Chernobyl nuclear accident on the
subsequent development of well-differentiated thyroid cancer.
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