| Background:Thyroid nodules are now a common clinical problem.The prevalence of thyroid nodules was estimated as 4-7%in general population on the basis of palpation.Since ultrasonography was introduced for clinical application,the prevalence of thyroid nodules has increased to 20-67%and approached 50%based on data reported in autopay.Althrough only around 5%of the clinically identified nodules are malignant, the main concern in evaluation of thyroid nodules is the verification of whether a lesion is benign of malignant,as for benign nodules,only conservative treatment is needed, but for malignancies,more aggressive treatment is needed.History and physical examination,laboratory evahaation are the basis of diagnosing thyroid nodules.Thyroid ultrasonography can detect nonpalpable nodules,differentiate simple cysts from solid nodules,determine the size of nodules during follow-up,and facilitate FNAB.Additionally,the noninvasiveness of the procedure has increased clinical application of this method for the evaluation of thyroid nodules.Intraoperative Frozen Section has value in diagnosing thyroid nodules,and is capable of determation of the extent of thyroidectomy.Paraffin section is the final pathology and is served as "gold standard" for diagnosing thyroid nodules.Pre- and intraoperative assement must be compared with paraffin section.Objective:To analyze the clinical and pathological characteristics of thyroid nodules and to evaluate the value of the present methods for diagnosing thyroid nodules.Research Design and Methods:SubjectsData from 1,474 consecutive patients,who underwent a thyroidectomy for nodular thyroid disease between March 2005 and October 2008 in the Shandong Provincial Hospital,were studied retrospectively.Subjects were 286 male and 1188 female patients(with a male-to-female ratio of 1:4.2),and had a mean age of(45.5±11.1) years.1450 of the 1474 patients were analyzed by US before surgery,others were not included in the study because of incomplete ultrasonographical information of their thyroid nodules or the absence of the US examination.Clinical evaluationHistory and physical examination such as family history,age,gender,duriation of thyroid nodules,symptom,careful thyroid palpation are made.Measurement of serum TSH,FT3,FT4,TPOAb and TGAb is also needed.UltrasonographyComplete high-resolution ultrasonographical information before surgery was collected from 1450 of the 1474 patients.All scans were performed by experienced radiologists with ultrasonographical scanners(IU 22 or Sonos 4500;Philips,Bothell, Wash.,USA) equipped with a 5- to 12-MHz linear-array transducer.Records for each patient included the number,size,location,morphology,boundaries and echogenic patterns of the nodules,the presence and patterns of calcification,as well as the internal blood flow and blood flow at the perimeter of the nodules.Both hyperechoic structures with acoustic shadowing(coarse calcifications) and very bright echoes without shadowing(microcalcifications) were considered evidence of calcifications.Pathology1460 patients had a intraoperative frozen section.All 1474 patients had a conclusive pathological diagnosis after surgery.A detailed gross description was made of all thyroid specimens before they were fixed in 10%neutral formalin.Tissue sections of 4 mm thickness were stained with HE.The pathological characteristics of all the nodules were confirmed by senior pathologists.Patients with a benign lesion accompanying the cancer were included in the malignant group.Results(1) There were 286 males and 1188 females.The ratio of male to female was 1:4.2. 1141(77.40%) patients were diagnosed with benign nodules and 333(22.60%) malignant nodules.The malignant rate was higher in males than in females(28.3%vs 21.3%,P＜0.05).The average age of malignant samples was younger than that of benign ones,the difference between which was significant(P＜0.05).(2) The mean TSH was 2.20±0.20mIU/L in patients with malignant nodules vs 1.76±0.08mIU/L in patients with benign nodules(P＜0.05)。The prevalence of malignance was 16.4%(11 of 67) when TSH was less than 0.40 mIU/L vs 34.3%(11 of 32) when TSH was 5.0mIU/L or greater(P＜0.05).Even in normal range,high rates of malignancy were found in patients with higher TSH levels.The prevalence of malignance were 21.6%(16 of 74) when TSH was between 1.90 and 2.49 mIU/L and 26.7%(31 Of 116) when TSH was between 2.50 and 4.99 mIU/L vs 16.5%(61 of 368) when TSH 0.40-1.89 mIU/L(P=0.34 and P=0.02,respectively).The mean TgAb and TPOAb were much higher in malignant nodules than that in benign nodules(TgAb:413.30±168.09 IU/mL vs 93.52±44.23IU/mL,P＜0.001; TPOAb:141.56±45.22 IU/mL vs 49.23±15.53 IU/mL,P＜0.001)(3) Most benign cases were diagnosed as nodular goiter(1034,90.6%),while most malignant nodules were diagnosed as papillary thyroid carcinoma(295, 88.6%)(4) The prevalence of thyroid cancer did not differ between patients with a solitary nodule and patients with multiple nodules(33.1%vs 27.6%,P=0.287).Those individual sonographic characteristics that showed a statistically significant difference in the malignant group were:ill defined margin,solid component,hypoechoic nodule, microcalcifications,internal blood flow and enlarged cervical lymph node(P＜0.001). There were no differences between the benign and malignant groups for absent of halo and coase calcifications(P＞0.05). (5) The accuracy,sensitivity,and disaccording rate of frozen section examinations was 96.0%,91.9%,0.5%,respectively.(6) Microcarcinoma was found in 68 patients by paraffin section examination,of which 26(38.8%) had lymph node metastases.Conclusions:(1) Thyroid nodules were found more often in women than in men,but the malignant rate was higher in men than in women.(2) The risk of malignancy in a thyroid nodule increases with higher serum TSH concentration.Even within normal ranges,a TSH level above the population mean is associated with greater llikelyhood of thyroid cancer than a TSH below the mean.(3) Ultrasonographic features could be helpful in differentiating benign and malignant nodules.Calcification detected by thyroid ultrasound represents a risk factor for malignancy,but is of limited use as a sole marker of malignancy.(4) Frozen section examination is of value in diagnosing thyroid nodules and play a key role in determination of extent of thyroidectomy.(5) Thyroid carcinoma often coexists with benign thyroid disease.Microcarcinoma can lead to misdiagnosis and disdiagnosis in ulrtasonograms and frozen section. |
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