Tall Cell Variant of Papillary Thyroid Carcinoma

Abstract

apillary thyroid carcinoma, the most common form of thyroid carcinoma (85% of cases), is well known for its indolent clinical behavior with a high survival rate compared to those of other malignancies. When papillary thyroid carcinoma with frequent recurrences and distant metastasis with aggressive clinical behavior is encountered, it has been pathologically diagnosed as a variant. 1-3 Among the variants of papillary thyroid carcinoma, the tall cell variant frequently has lymph node metastasis, distant metastasis, or both, with a strong association with a poorer prognosis, 4-12 behaving very differently from indolent or conventional papillary thyroid carcinoma.The definition of the tall cell variant of papillary thyroid carcinoma was first proposed by Hawk and Hazard 13 as the presence of a papillary tumor whose cells are at least twice as long (tall) as they were wide. Since then, other pathologists have proposed more stringent criteria to diagnose the tall cell variant, including a composition of more than 50% tall cells, with a tall cell height of at least twice the width, eosinophilic tall cell cytoplasm, and nuclear features characteristic of papillary thyroid carcinoma. 14 This subtype, which constitutes less than 5% of all papillary thyroid carcinomas, 15 had not been studied much because of its rarity and difficult diagnosis, even with its aggressive clinical features and high mortality rates.A study performed in Japan suggested that an unidentified endemic factor is responsible for the lower prevalence and independent poor prognostic factors of the tall cell variant. 7 The aims of this series were to describe the clinical characteristics of the tall cell variant of papillary thyroid carcinoma and to characterize its highresolution sonographic features. Medicine, CASE SERIESWe retrospectively reviewed the clinical and sonographic features of 8 patients with 10 tall cell variants of papillary thyroid carcinoma. The mean age of the patients was 57 years (range, 34-72 years). The tumor sizes varied. Of the 8 patients, 5 had symptomatic masses, and 3 had incidentalomas. Three patients had recurrences and 1 died of pulmonary metastasis within a mean time of 30 months. The tall cell variants often appeared as microlobulated markedly hypoechoic nodules with microcalcifications and extrathyroidal extension on sonography and were always associated with lymph node metastasis. The tall cell variant of papillary thyroid carcinoma should be included in the differential diagnosis of an aggressive thyroid tumor with symptoms and cervical nodal metastasis.

Aggressive variants of papillary thyroid cancer

“…Accurate preoperative diagnosis has been difficult to secure. Choi et al [15] studied in a retrospective fashion the clinical and sonographic features of eight patients with 10 TCV tumors. The inclusion criteria for a diagnosis of TCV included a tumor 'composed of more than 50% tall cells, a tall cell height at least twice its width, eosinophilic tall cell cytoplasm, and nuclear features characteristic of papillary thyroid carcinoma such as nuclear irregularities, clearing and overlapping, grooves, and pseudoinclusions'.…”

Tall cell variant of papillary thyroid carcinoma: current evidence on clinicopathologic features and molecular biology

“…Due to the rarity of TCV, only one study [23] reported the distinctive sonographic appearance of this variant to date. In that study, Choi et al reviewed the sonographic features of 10 TCV and found that TCV always associated with microlobulated, markedly hypoechoic solid nodules, extrathyroidal extension and lymph node metastasis.…”

A comparison of the clinicopathological features and prognoses of the classical and the tall cell variant of papillary thyroid cancer: a meta-analysis

“…Classic TCV tumors are “composed of more than 50% tall cells, a tall cell height at least twice as long as its width, eosinophilic tall cell cytoplasm, and nuclear features characteristic of PTC such as nuclear irregularities, clearing and overlapping, grooves, and pseudoinclusions” [29]. Preoperative sonographic findings indicative of TCV often overlap significantly with those indicative of cPTC, but TCV often harbors features that are more aggressive, such as hypoechogenicity, evidence of ETE, microcalcifications, and macrocalcifications.…”