Unusual Thallium-201 and Sonographic Patterns in a Thyroidectomized Papillary Thyroid Cancer Patient with Cervical Nodal Involvement: A Case Report and Literature Review

Received 9/19/2004; revised 10/2/2004; accepted 10/6/2004. For correspondence and reprints contact: Wen-Sheng Huang, M.D., Department of Nuclear Medicine, Tri-Service General Hospital, 325 Section 2, Cheng-Kung Road, Neihu, Taipei 114 Taiwan, ROC. Tel: (886)2-287927374, Fax: (886)2-287927217, E-mail: [email protected] A 26-year-old woman who had received a thyroidectomy due to papillary thyroid cancer was recently found to have abnormal serum thyroglobulin levels and was referred to our Department for a cancer work-up. The early (10 min) phase thallium-201 (Tl) scan showed increased uptake in the right lower neck region but it returned to background level in the delayed phase (2 h). The retention index (RI) was -28. The concominent neck sonography showed no abnormality except for a small remnant in the left thyroid bed. F-FDG PET was negative. However, the patient felt the sensation of a foreign body around the anterior neck region after a 3week T4 withdrawal. A repeated sonography showed 3 hypervascular, enlarged nodes which corresponded to the previous Tl uptake sites. The largest one measured 2.2 1.2 1 cm in size with central hypervascularity. Metastatic papillary thyroid cancer was further diagnosed by T4 withdrawal I scan. The increased Tl uptake in the early phase might be due to hypervascularity of the tumor. However, the Tl image patterns appeared to contradict with the usual. Cervical sonography and F-FDG PET could be negative in above mentioned and patients on T4 settings. Such patterns could be commonly found in relatively benign carcinomas such as well-differentiated thyroid carcinoma and should be interpreted with caution.