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Home , Thyroid adenoma

Unusual Scintigraphic Findings in a

Sumathi Murthy, Jeffrey I. Mechanick, Peter Chau, Stanley J. Goldsmith and Peter Webner

Department ofNuclear Medicine, Division ofEndocrinology and Metabolism, Mount Sinai Medical Center, New Yorlç New York

visualized, indicating suppression of normal thyroid tissue (Fig. Thallium imaging is increasingly being used to evaluate the 1) consistentwith the diagnosisof an autonomousnodule.Im thyroid. Uptake patterns of @°1Tlin benign and malignant aging with 201Tlwas performed 15—20mm following administra thyroid nodules have been described. Thallium localizes all tion of 2 mCi of @°‘Tl.Anterior image of the thyroid was ob thyroid tissue with possibly different rates of washout in be tamed using a pinhole collimator for 50,000 counts. The scan nign and malignant nodules. This case demonstrates a fol revealed lack of tracer uptake in the region of the nodule, while licular adenoma presenting 1@las a clinically palpable nod the surrounding thyroid tissue not visualized on ‘@Iscintigraphy ule with nonvisualization of the remainder of the thyroid gland showed good tracer uptake (Fig. 2). Since both lobes of the consistent with the diagnosis of an autonomously hyperfunc thyroid were visualized on the thallium study, the nodule was tioning module. Subsequent thallium scanning revealed a localized at the inferior pole of the right lobe. The patient un complete reversal of tracer distribution with lack of uptake of derwent surgical excision of the nodule. Microscopic examina 20111 in the nodule while the rest of the gland showed normal tion of the nodule revealed a benign follicular adenoma with thallium accumulation. Surgical excision of the nodule dem extensive cystic degeneration (Fig. 3). onstrated follicular adenoma. DISCUSSION J NucIMed 1993;34:465-466 This case illustrates the complex relationship between histology and functional images. Thallium is known to accumulate in normal thyroid tissue as well as thyroid (4—9).Several other tumors also have been tonomously functioning thyroid nodules are most shown to accumulate thallium (10—12).Several mecha commonly adenomatous nodules and are very rarely car nisms influence thallium uptake by neoplastic tissue, in cinomas (1,2). However, functioning thyroid nodules are cluding tissue perfusion, sodium-potassium ATP-ase almost always benign (3). Recent reports have described transport mechanism and tissue viability (13—15).This dif uptake characteristics of @°‘Tlin thyroid nodules in an fers from the mechanism of iodine uptake by the thyroid effort to distinguish between benign and malignant nod which includes TSH-dependent, active, iodide transport ules (4—6).From these reports, it is apparent that all across the cell membrane and subsequent organification. thyroid nodules show early accumulation of thallium, In this patient, the 1@Ithyroid scan indicated a func although the rate of tracer washout varies in the delayed tioning . Early thallium accumulation in images. We present an unusual case with discordance of this area would have been expected but was not ob 1231 and @°‘Tlimages of the thyroid nodule. served. In fact, the hyperfunctioning nodule localized less @°‘Tlthan the surrounding, metabolically suppressed CASE REPORT thyroid. Although the lack of such uptake in this instance A 63-yr-old male was evaluated for fatigue and weight loss. is initially puzzling, histopathologic examination of the His physical exam was unremarkable except for a 2-cm right nodule showing extensive cystic degeneration explains sided thyroid nodule. His thyroid function tests revealed a nor the paucity of thallium uptake in the nodule (i.e., the mal T4, slightly elevated T3 and a low TSH. Fine needle aspi ration biopsy (FNAB) of the nodulewas suspiciousfor a thallium image reflects overall viable tissue distribution in Hurthle cell . Both ‘@-@Iand 20―fl scintigraphy were the gland and the density of the viable tissue is consider performed because of the suspicion of a malignant nodule as ably less in the nodule in comparison with the surround indicated by FNAB. The ‘@Ithyroid scan revealed uniform ing normal tissue). Also, the presence of necrosis has tracer uptake in the nodule. The rest of the gland was not been explained as a possible explanation for poor thaI hum concentration which could be due to nonfunctioning

Received Jul. 7, 1992; revisIon accepted Nov. 5, 1992 ATP-ase cell membrane pump activity (14,15). The iodine For correspondence contact Sumathi Murthy,MD,MountSinai Medical image by contrast reflects the degree of active iodine Center,DepartmentofNuclearMedicine,BoxI141, OneGustaveL LevyP1, New York, New York 10029. incorporation. The activity of the iodide transport mech Reprints are not available from the author. anism in the thyroidal cells is dependent on circulating

Findings in a Thyroid Adenoma •Murthy et al. 465 @ •@4@S@)@ @•-@@:

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FiGURE 1. Iodine-i 23 thyroidscanshowsuptakein the right ACKNOWLEDGMENT sided thyroid nodule with lack of uptake in the remainderof the The authors thank Dr. Pamela Unger of the Department of gland. Arrows point to sternal notch and right side markers. for providing the excellent microphotographs.

TSH levels. Low TSH levels such as in this patient would REFERENCES minimize transport across normal thyroid tissue, with little or no effect on the autonomous nodule and might 1. Werner S, Ingbar S. The thyroi4 a fundamental and clinical text, 6th edition. Hagerstown, MD: Harper and Rowe; 1991:698—699. thus enable the nodule to accumulate much higher con 2. Kahn 0, ElI PJ, Maclennan KA, Kurtz A. Thyroid carcinoma in an centrations of radioiodine than adjacent normal thyroid autonomouslyhyperfunctioningthyroid nodule. Post Grad Med I 1981; tissue to mask the presence of degenerating, nonviable 57:172—175. 3. Ross D. Evaluation of the thyroid nodule [Editorial] I Nuci Med 1991; tissue within the nodule. 32:2181—2192. This case illustrates the potential complexity which 4. Tonami N, Bunko H, Michigishi T, et al. Clinical application TI scmntig may be encountered in imagingthyroid noduleswith thal raphy in patients with cold thyroid nodules. CliiiNucl Med 1978;3:217— 221. hum or dual-isotope imaging when there are different 5. Ochi H, Sawa H, Fulcude T, et al. 11-201-chloride thyroid scintigraphy to physiologic pathways involved in tracer binding. evaluate benign and/or malignant nodules. Cancer 1982;50:236—240. 6. HardoffR, BaronE, SheinfeldM. Early and late lesion-to-nonlesionratio of 11-201-chlorineuptake in the evaluationof “cold―thyroid nodules.I Nuci Med 1991;32:1873—1876. 7. Hofnagel CA, Delprat CC, Noncuse HR. et al. JJM: role of thallium-201 total body scintigraphy in follow-up of thyroid carcinoma. J Nuci Med 1986;27:1854. 8. Tomani N, Hisada K. 11-20! scintigraphy in postoperative detection of : a comparison study with 1-131. Radiology 1980;136:461. 9. MichigishiT, MizukamiY, MuraT, et al. Papillarycarcinomain ectopic thyroid detected by 11-201 scintigraphy. Clin Nucl Med 1991;16:337—339. 10. WaxmanAD, RamannaL, Eller D. Characterizationof lymphomagrade using thallium and gallium scintigraphy [Abstract]. I Nuci Med 1991;32: 917—918. 11. BlackKL, RandallAH, KimKT, BeckerDP, Lerner C, MarcianoD. Use of thallium-201SPECT to quantitate malignancy grade of gliomas. J Neumsurg 1989;71:342—346. 12. Muller SP, Reiner C, Paas M, et al. Tc99m-MIBI and 11-201 uptake in bronchial carcinoma [Abstract]. I Nuci Med 1989;30:845. 13. Kaplan WD, Kvorian T, Morris JH, Rumbough CL, Connolly BT, Atkins —V-@• HL. Thallium-201brain tumor imaging:a comparativestudy with patho @ -‘-.‘j,', logic correlation. I Nucl Med 1987;28:47—52. 14. Scheweil AM, McKillop JH, Milroy R, Wilson R, Abdel-Dayem HM, Omar YT. Mechanism of Tl-201 uptake in tumors. Eur I NucI Med 1989;15:376—379. FIGURE 2. Thallium-20iscan of the thyroidshowsde 15. Ando A, Ando I, Katayama M, et al. Biodistribution of 2°'Tlin tumor creased uptake in the nodule and normal uptake in the remain bearing animals and inflammatory lesion induced animals. Eur I Nuci der of the gland. Med 1987;12:567—572.

466 The Journal of Nuclear Medicine •Vol. 34 •No. 3 •March 1993