As for other solid tumors, malignant cutaneous melanoma drains in a logical way through the lymphatic system, from the first to subsequent levels. Therefore, the first lymph node encountered (the sentinel node) will most likely be the first to be affected by metastasis, and a negative sentinel node makes it highly unlikely that other nodes in the same lymphatic basin are affected. Sentinel lymph node biopsy distinguishes patients without nodal metastases, who can avoid nodal basin dissection with its associated risk of lymphedema, and those with metastatic involvement who might benefit from additional therapy. This procedure represents a significant advantage as a minimally invasive procedure, considering that only an average 20% of melanoma patients with Breslow thickness between 1.5 and 4 mm harbour metastasis in their sentinel node(s) and are therefore candidates to elective lymph node dissection procedures. The cells that originate cutaneous melanomas are located between dermis and epidermis, a zone that drains to the inner lymphatic network in the reticular dermis, in turn to larger collecting lymphatics in subcutis. Therefore, the optimal modality of interstitial administration of radiocolloids for lymphoscintigraphy and subsequent radioguided sentinel lymph node biopsy is through intradermal/subdermal injection. (99m)Tc-labeled colloids in various size ranges are equally adequate for radioguided sentinel lymph node biopsy in patients with cutaneous melanoma, depending on local experience and availability. For melanomas located in the midline area of the head, neck, and trunk, particular consideration should be given to ambiguous lymphatic drainage, which frequently requires interstitial administration virtually all around the tumor or surgical scar from prior excision of the melanoma. Lymphoscintigraphy is an essential part of radioguided sentinel lymph node biopsy because images are used to direct the surgeon to the sites of the node(s). The sentinel lymph node should have a significantly higher count than that of background (at least 10:1 intraoperatively). After removal of the sentinel node, the surgical bed must be reexamined to ensure that all radioactive sites are identified and removed for analysis. The success rate of radioguidance in localizing the sentinel lymph node in melanoma patients is about 98% in institutions where a high number of procedures are performed, approaching 99% when combined with the vital blue dye technique. The procedure is becoming the standard of care for patients with cutaneous melanoma because of its high prognostic value that has led to include the procedure in the most recent version of the TNM staging system.

Although (18) FDG-PET/CT scans are more likely to be positive with pretest Tg levels ≥4.6 ng/mL, 11% of patients with DTC with a lower serum Tg level will still have a positive scan. Our findings are in contrast with the American Thyroid Association (ATA) guidelines, which only recommend to perform (18) FDG-PET/CT in patients with Tg levels >10 ng/mL.

Based on our data we conclude that pre-ablative onT4-Tg is a prognostic marker and should be used instead of pre-ablative TSH-stimulated Tg measurement when rhTSH-aided radioiodine ablation is done.

Thyroglobulin (Tg) measurement on fine-needle aspiration (FNA) specimens (Tg-FNA) is useful in the management of patients affected by differentiated thyroid carcinoma. However, the preanalytical procedure for FNA-Tg measurement is not standardized. We evaluated the accuracy of FNA-Tg measurement by using different tubes for needle washout fluids collection.Ultrasound-guided FNA was performed on a combined 156 lesions from 108 patients. Following cytology sampling, the needles were rinsed by normal saline and aliquots collected into three different tubes (plain serum tube, serum separator tube, and lithium-heparin tube, respectively). The Tg-FNA was measured by an immunoradiometric assay.The cytological examination was nondiagnostic in six cases, false-positive in one, and false-negative in two cases. The Tg-FNA was higher in plain serum tubes as compared with serum separator and lithium-heparin ones. FNA-Tg measurement on plain serum and serum separator tubes showed a 100% sensitivity while two false-negative results occurred by lithium-heparin tubes (sensitivity 98%).The diagnostic performance of FNA-Tg compared favorably with cytology. However, biases in FNA-Tg measurement may be introduced by different collection tubes. A collection of standardized washout fluids volume into plain serum tubes is highly recommended. Serum separator tubes and lithium-heparin tubes may lower measured FNA-Tg concentration. Diagn. Cytopathol. 2009;37:42-44. ' 2008 Wiley-Liss, Inc.Key Words: thyroglobulin; fine-needle aspiration; cytology; thyroid carcinoma; lymph nodesThe thyroglobulin (Tg) is a large glycoprotein stored in the follicular colloid of the thyroid gland acting as a prohormone in the intra-thyroid synthesis of thyroid hormones. It is produced only by normal thyrocytes or well differentiated thyroid cancer cells, and its tissue-specific origin predicates the clinical value of Tg testing. Serum Tg detection after thyroid ablation indicates the presence of residual healthy thyroid tissue or metastatic disease. Thus, important clinical decisions such as whether patients should undergo diagnostic or therapeutic procedures are based on the measurement of the serum Tg concentration in individual patients. 1 Typically measured with immunometric assays, Tg concentration can be falsely lowered due to interference from anti-Tg antibodies (Tg-Ab) or hook-effect while results can be spuriously high due to interference from heterophile antibodies. 2 Additionally, several preanalytical effects (e.g. freezing or repeated freezing and thawing of sera, hemolysis or lipemia, preanalytical use of different serum separating tubes) could affect the Tg measurement in serum. 3 Recently, the Tg measurement on fine-needle aspiration (FNA) washout fluids (FNA-Tg) showed to be useful in the management of patients affected by differentiated thyroid carcinoma (DTC). 4,5 Cunha et al. 6 evaluated 83 enlarged cervical lymph-nodes from 67 patients affected by DTC: the FNATg showed a sensitivity of 100% while cytology alone missed 9 of 20 DTC metast...

A negative MIBI scan in a cold nodule accurately excludes malignancy when US-FNAC is reported as nondiagnostic. This avoids the need for more invasive diagnostic procedures (ie, surgery) and positively influences the cost-effectiveness profile. A MIBI scan may be performed by acquiring images 30 minutes after tracer administration alone. Histology is still necessary to distinguish benign from malignant disease in a MIBI-positive nodule but unnecessary surgery could have been reduced from 71 to 8 cases in our series.

A careful assessment of interferences in Tg measurement significantly reduced the occurrence of undetectable Tg among patients with ¹³¹I uptake in PT-WBS. However, such extensive assessment is difficult in clinical practice and one-fifth of patients still had undetectable Tg in multiple assays despite an intensive laboratory work-up. A benchmark between ¹³¹I imaging and Tg measurement authenticates the interpretation of Tg measurements and, consequently, remains of pivotal value by authenticating the use of serum Tg during further follow-up of DTC patients.

Aim. Enlarged cervical lymph nodes (LNs) in patients with thyroid cancer are usually assessed by fine-needle aspiration cytology (FNAC). Thyroglobulin (Tg) is frequently elevated in malignant FNAC needle wash specimens (FNAC-Tg). The objectives of the study were to (1) determine an appropriate diagnostic cut-off for FNAC-Tg levels (2) compare FNAC and FNAC-Tg results in a group of 108 patients affected by differentiated thyroid carcinoma (DTC). Methods. A total of 126 consecutive FNACs were performed on enlarged LNs and the final diagnosis was confirmed by surgical pathology examination or clinical follow-up. The best FNAC-Tg cut-off level was selected by receiver operating curve analysis, and diagnostic performances of FNAC and FNAC-Tg were compared. Results. The rate of FNAC samples adequate for cytological examination was 77% in contrast FNAC-Tg available in 100% of aspirates (P < .01). The sensitivity, specificity, and accuracy of FNAC were 71%, 80%, 74%, 100%, 80%, and 94%, respectively. The most appropriate cut-off value for the diagnosis of thyroid cancer metastatic LN was 1.1 ng/mL (sensitivity 100%, specificity 100%). Conclusions. The diagnostic performance of needle washout FNAC-Tg measurement with a cut-off of 1.1 ng/mL compared favorably with cytology in detecting DTC node metastases.

The (⁹⁹m) Tc-pertechnetate scintigraphy is a simple and feasible tool to evaluate thyroid remnants and to predict radioiodine ablation results in patients with DTC.