Thyroglobulin detection in fine-needle aspirates of cervical lymph nodes: a technique for the diagnosis of metastatic differentiated thyroid cancer

Abstract

Background: Fine-needle aspiration cytology is frequently used for differential diagnosis of neck masses of unknown origin. Inconclusive and even false-negative results are not uncommon. Aim: To evaluate the utility of thyroglobulin (Tg) measurement in fine-needle aspirates (FNA-Tg) for detecting cervical lymph node (CLNs) metastases from differentiated thyroid carcinomas. Methods: An ultrasound-guided fine-needle aspiration was done in 67 patients with 83 suspicious enlarged CLNs to obtain material for cytology and Tg measurement in the needle washout, using an immunometric chemiluminescent assay. Measurement of anti-Tg antibodies (FNA-TgAb) was also carried out in half of all the aspirates. Subjects were divided into two groups: one of 16 patients awaiting thyroidectomy and the other of 51 patients in follow-up after surgery. Results: The first group of patients had positive FNA biopsy (FNAB-Tg) in 14 out of the 18 studied CLNs with a range of 3.2-43 352 ng/ml, while FNAB-cytology indicated metastasis in only 8 out of the 14 CLNs with positive histology. A total of 65 CLNs were studied in the follow-up group. Lymphadenectomy was performed in 23 patients and 28 aspirated CLNs were removed. Histology confirmed the diagnosis of metastasis suggested by FNAB-Tg in 20 CLNs and of reactive lymphadenitis in the remaining 8 CLNs. FNAB-cytology was positive in only 11 CLNs. Sensitivity of FNAB-Tg was not affected by the studied FNAB-TgAb. Conclusions: The FNAB-Tg achieved a sensitivity of 100% in both groups. FNAB-Tg is an easy and inexpensive technique which proved to increase the diagnostic of cytology in the early diagnosis of papillary carcinoma recurrence to CLN even in the presence of serum TgAb.

Thyroglobulin measurements in washout of fine needle aspirates in cervical lymph nodes for detection of papillary thyroid cancer metastases

“…Cutoffs used in previous studies have varied widely, without a consensus about the most appropriate level (6,19,20). However, a recent study with 168 patients that analyzed 4 different levels of cutoffs (1, 10, 100 ng/mL and FNAB-Tg mean ± SD) indicated that the best level for diagnosis of DTC persistence/recurrence was < 10 ng/mL (16).…”

“…(21) that demonstrated that sTg interferes with FNAB-Tg measurement only when high sTg levels are present. These authors, based on recent studies (19,20), suggest that in all patients who do not have high levels of sTg, a detectable level of FNAB-Tg …”

Lowered cutoff of lymph node fine-needle aspiration thyroglobulin in thyroid cancer patients with serum anti-thyroglobulin antibody

“…We compared sensitivity, specificity, PPV, NPV and diagnostic accuracy of FNA-Tg levels of LN according to the functional sensitivity of Tg (0.7 ng/ml) (3,22) and the value determined by ROC curve (6.0 ng/ml), with those of FNAC (Table 4). In addition, FNA-Tg/sTg ratio was also used as a cut-off value to diminish the influence of sTg in preoperative patients (19,23) (Table 4) FNAC alone showed the lowest sensitivity (88.4%) but the highest specificity (99.6%).…”

“…Fine needle aspiration cytology (FNAC) is recommended for diagnosis of metastatic LNs in thyroid cancer (3,4). When Positive serum Tg antibody (TgAb) is known to lower serum Tg (sTg) levels, and this may be even more important in DTC patients prior to thyroidectomy and/or radioactive iodine therapy in whom a higher rate of positive TgAb has been reported (17).…”

Clinical impact of thyroglobulin (Tg) and Tg autoantibody (TgAb) measurements in needle washouts of neck lymph node biopsies in the management of patients with papillary thyroid carcinoma

“…These results may occur in cases of small or cystic LN metastases, which reflect a lack of tumor cells detected during the FNAB procedure (11). Nevertheless, the use of Tg-FNAB alone has several limitations, and despite being well established as an important tool in the investigation of suspicious LN metastases, Tg-FNAB presents variable results between metastatic and non-metastatic LNs (3,4,(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23). This subject has been the topic of recent reviews and meta-analysis studies (12,13).…”