Scintigraphic Visualization of Glossal Thyroid Tissue During the Follow-up of Thyroid Cancer Patients

Abstract

When examining whole-body scans (therapeutic or diagnostic) in a patient with persistent Tg detection after thyroid ablation, one should carefully search for any uptake between the submandibular glands that may be suggestive of ectopic tissue.

Concurrent lingual thyroid and undescended thyroglossal duct thyroid without orthotopic thyroid gland

“…Similarly, lingual thyroid may masquerade as metastasis on thyroid scan. A study of 548 patients undergoing whole‐body scan following total thyroidectomy and radioiodine ablation therapy showed a 0.9% incidence of ectopic thyroid tissue in the tongue or upper part of the thyroglossal duct 6. Lingual thyroid may occasionally undergo massive hypertrophy resulting in airway obstruction.…”

Differentiated Thyroid Carcinoma with Elevated Thyroglobulin and Negative Radioiodine Whole-Body Scan Metastases

“…Apart from their ability to interfere with Tg assays, benign lesions (possibly with foci of thyroiditis) in persistent residual thyroid tissue or non-thyroidal tissue producing Tg may also result in false-positive Tg in DTC patients. However, residual occult disease is usually the source of post-operative Tg elevations [28][29][30]. Rarely, TSH-stimulated thymus may produce Tg [6].…”

“…The thyroglossal tract is the most common location for ectopic thyroid tissue. This tissue retains Differentiated Thyroid Carcinoma with Elevated Thyroglobulin and Negative Radioiodine Whole-Body Scan Metastases http://dx.doi.org/10.5772/64356 not only the ability to concentrate iodine, but also to produce Tg and release it into the bloodstream [28,31,32]. The iodine metabolism-related proteins such as human sodium/ iodide symporter (hNIS) [33], TSH receptor at both mRNA and protein level [6] are present in non-thyroidal tissues, including the thymus.…”

“…Usually, these functions are dormant, but they Thyroid Cancer -Advances in Diagnosis and Therapy may be activated by TSH stimulation [34]. Interestingly, these extra-thyroidal foci may be resistant to multiple 131 I treatments [28,31,32]. In a series of 548 consecutive diagnostic WBS, ectopic thyroid tissue in the tongue or in the upper part of the thyroglossal duct was visualized in five patients (0.9%) [28].…”

A low thyroglobulin level cannot be used to avoid adjuvant 131I therapy after thyroidectomy for thyroid carcinoma

“…A limitation of the study is that in the majority of patients no guided biopsy of 131 I foci was obtained. So one cannot formally exclude the possibility that some of these patients may have had residual noncancerous thyroid tissue located outside the thyroid bed, for example substernal goitre or ectopic foci along the thyroglossal duct [5].…”