Papillary thyroid microcarcinoma is a particular form of cancer of the thyroid gland. This term, according to the WHO classification, is applied to papillary tumors no larger than 1.0 cm in diameter, which are incidentally detected during the postoperative histopathological examination. In clinical practice, the term pertains to all papillary tumors of the size smaller than or equal to 1 cm.
<bold>The aim of the study</bold> was to determine the prevalence of papillary thyroid microcarcinoma and its selected histopathological characteristics among patients with malignant cancer of the thyroid gland identified in our own material in the years 2000-2007.
<bold>Material and methods.</bold> The study included 523 patients treated for thyroid carcinoma: 401 (76.7%) women and 122 (23.3%) men aged 12-83 years (mean 49.8 years). Surgeries were carried out according to the Polish Group for Endocrine Carcinomas recommendations, in compliance with the European consensus.
<bold>Results.</bold> Papillary thyroid carcinoma was identified in the postoperative histopathological examination in 391 (74.8%) patients; 285 (72.9%) women and 106 (27.1%) men. Their age ranged from 14 to 75 years (mean 49.3 years).
Among 391 cases, tumor progression classified according to the WHO criteria (3) was as follows: T1 in 260 (66.5%), T2 in 59 (15.1%), T3 in 53 (13.5%) and T4 in 19 (4.8%) patients.
In 150 cases (38.4% of papillary tumors), the tumor fulfilled the morphological criteria for microcarcinoma (4) and was detected in 118 (78.7%) women and 32 (21.3%) men. Carcinoma was identified in the neutral goiter in 138 cases, and in 12 patients in hyperactive, including 9 in nodular and 3 in Graves' goiters. The disease was suspected or diagnosed preoperatively or at surgery in 112 patients. Postoperative diagnosis was performed in 38 (25.3%) individuals with micrcarcinoma. Twenty-four (38%) of 63 patients with multifocal tumors were subjected to adjunctive surgery as their cancer diagnosis was made only postoperatively in the histopathological examination. The subcapsular location of microcarcinoma was found in 78 (49.4%) cases including capsular infiltration and extracapsular invasion in 14 patients. The exact histopathological examination showed multifocality in 63 (42%) cases and involvement of the local lymph nodes in 29 (19.3%) patients. In 21 cases, the central compartment lymph nodes were involved. The presence of metastases in the central and lateral lymph node compartment was observed in 5 cases; in 3 patients skip metastases were detected in the lateral compartment on the tumor side omitting the central compartment. No patient with microcarcinoma diagnosed between the years 2000 and 2007 revealed distant metastases.
<bold>Conclusions.</bold> Due to contemporary diagnostics, papillary thyroid microcarcinomas - tumors up to 1 cm - are most commonly identified cancers of the thyroid gland. High accuracy of US-guided fine-needle aspiration biopsy of high resolution permits to diagnose the majority of these tumors prior to surgery.
Financed by the National Centre for Research and Development under grant No. SP/I/1/77065/10 by the strategic scientific research and experimental development program:
SYNAT - “Interdisciplinary System for Interactive Scientific and Scientific-Technical Information”.