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CaseReports Hyperthyroidism Caused by a Toxic Intrathoracic Goiter with a Normal-Sized Cervical Gland

R. Prakash, N. Lakshmipathi, A. Jena, V. Behari, and M.K. Chopra Medical Division, Institute ofNuc!ear Medicine and Allied Sciences, Delhi, India

The rare presentation of hyperthyroidism caused by an intrathoracic goiter with a normal sized cervical thyroid gland is described. The toxic intrathoracic goiter demonstrated avid uptake of [1311]and [@“Tc]pertechnetate,with comparatively faint isotopic accumulation seen in the cervical thyroid. A chest roentgenogram and radioisotope scan should be mandatory in casesof hyperthyroidismhavingno cervicalthyroidenlargementto explorethe possibilityof a toxic intrathoracicgoiter.

J NucI Med 27:1423—1427,1986

ntrathoracic goiter most commonly presents as a CASE REPORT @ superior mediastinal mass and accounts for 10% of all mediastinal masses (1,2). Pathological studies have A 52-yr-old female presented with a 4-mo history of weak shown that intrathoracic goiters almost always occur as ness,weightlossin spiteofa normalappetite,and twoepisodes a result of inferior extension of thyroid tissue in the of hemoptysis. There were associated symptoms of increased neck (3). The connection between intrathoracically bowel frequency, nervousness, , , and placed goiters and the cervical gland is clearly demon tremulousness. Physical examination revealed a slightly female strable in the majority ofcases (4,5), which are classified in no distress, blood pressure was 140/90 mmHg supine, as secondary intrathoracic goiters. Completely sepa 96 and regular. Her skin was warm and moist, and she had rated, aberrant, or primary intrathoracic goiters arise fine finger . A mild lid lag and lid retraction was from ectopic tissue which has separated from the gland evident on the right side. There was no palpable goiter. proper during embryonic life and descended into the Chest x-ray (Figs. 1 and 2) showed a 6 x 5 cm diameter mediastinum (6,7). mass in the right superior middle mediastinum with central Intrathoracic goiters may be asymptomatic and dis calcification. There was no significant tracheal compression covered incidentally, but may cause clinical symptoms or displacement. due to pressure on adjacent structures as the goiter Laboratoryinvestigationsconfirmedthe clinicaldiagnosis enlarges within the rigid thoracic inlet (8). These goiters of hyperthyroidism.Thyroid hormone estimation done by are usually nontoxic nodules; hyperthyroidism has been radioimmunoassay showed serum total tniodothyronine level of 390 ng/dl (normal range 70—220ng/dl) and serum reported to be an unusual accompaniment ranging from thyroxine of2l @zg/dl(normal 5—13.5). 0 to 15% in recent series (4,5). However, all these Thyroid radioactive uptake (RAIU) was measured reported cases had enlarged thyroid glands in the neck. over the neck with a single channel analyzer and as per IAEA We report a case of intrathoracic goiter causing hy recommendations (9). The uptake after oral administration perthyroidism and feedback suppression of a normal of25 @@Ciiodine-131 (‘31I)was15% at 2 hr and 34% at 24 hr. sized cervical thyroid gland. Radioisotope scans showed A gamma camera thyroid scan was done at 24 hr (Fig. 3) faint continuity ofthe intrathoracic mass with the lower using an 8-mm aperture pinhole collimator positioned 7 cm pole of the right lobe of the thyroid. A review of the abovethe suprasternalnotch. A 10-mmcount imageshowed literature is presented. a functioning intrathoracic goiter on the right side in the position corresponding to that of the mediastinal mass oh served on the chest x-ray. The central area had reduced activity Received Oct. 7, 1985: revision accepted Mar. 31, 1986. consistent with degeneration. Faint radioactivity was observed For reprints contact: Rajeev Prakash, MD, Scientist ‘C',Insti in the normal-sized cervical thyroid. Iodine-131 uptake mea tute ofNuclear Medicine and Allied Sciences, Probyn Rd., Delhi sured with the probe now focused over the mediastinal mass I10007,India. was 32%.

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FIGURE 1 Posteroanteriorroentgenogramshowshomogenousmass in superiormediastinumto rightof midlineproducingmm imal impressionon tracheawith no significantdisplace FIGURE 2 ment Lateral view demonstrates mass to be in middle medias tinum with evidence of central calcification. There is no significant tracheal compression A technetium-99m (99mTc)pertechnetate thyroid scan was obtained after i.v. administration of5 mCi ofthe radionuclide. A 400,000-count pinhole image showed intense isotopic up ectopic or so-called primary intrathoracic goiters are take in the intrathoracic nodule with few central areas of reduced, patchy uptake suggestive of multinodularity (Fig. 4). extremely rare (6,12) and presumably originate from Comparatively faint accumulation of the radionuclide was fragmented embryonic thyroid tissue that has seen in the cervical thyroid. descended into the mediastinum ( 7). A diagnosis of hyperthyroidism due to a hyperfunctioning Intrathoracic goiters occur most commonly in the intrathoracic goiter with a normal-sized cervical thyroid gland fifth decade of life (10) with a female predilection of 3 was made. The patient was initially treated with graded doses to 4: 1 (5). These may be completely asymptomatic in of with good improvement. As there was no 15—50%ofcases (3,13). Clinical manifestations include obvious tracheal compression, nor any pressure symptoms, hoarseness, cough, dyspnoea, and stridor (5,10,14) and she was subsequently treated with 15 mCi of [‘311]sodiumdysphagia may occur in ½of cases. The rarer presen iodide. Four months after radioiodine therapy the patient was tations include superior vena cava syndrome (15), clinically and biochemically euthyroid ( 200 (16), and hyperthyroidism (1 7). ng/dl, thyroxine 12 @zg/dl). Earlier reports have shown that fewer than 10% of substernal goiter patients had elevations in thyroid hor DISCUSSION mone levels (4). More recent series have shown only an occasional hyperthyroid patient (10,18). However, all Intrathoracic goiter is one ofthe major considerations these patients had associated cervical thyroid enlarge in the evaluation of superior mediastinal masses. Sub ment and could be classified as having secondary intra sternal and partial intrathoracic goiters generally rep thoracic goiters. In the case cited by Ng Tang Fui et al. resent intrathoracic extensions ofcervical thyroid tissue (18) it is obvious on the thyroid scan performed after (10); 75—80%of these masses descend into the anterior radioiodine therapy that the intrathoracic goiter was an mediastinum while the remainder descend into the extension of the enlarged left lobe of the thyroid gland. posterior mediastinum (11) with middle mediastinal Our patient presented with classic features of hyperthy goiters being rarely encountered. Completely separated, roidism, confirmed by . Thyroid

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FIGURE4 FIGURE3 Technetium-99m pertechnetate thyroid scan shows avid Iodine-i 31 thyroid scan shows hyperfunctioning intratho uptakeby intrathoracicnodulewith centralpatchyareas. racic goiter on right side with comparatively faint uptake Faint continuity with nght lower pole of cervical thyroid is in normal-sizedcerv@althyroid seen

scan conclusively demonstrated a normal-sized thyroid in 99mTc images the high blood background from the gland with increased uptake in the intrathoracic goiter cardiovascular blood pool can interfere with the scan located in the superior mediastinum. quality and visualization of a retrosternal thyroid. The The diagnostic procedures currently in use for eval role of isotopes is, however, controversial as negative uation of intrathoracic goiter include chest radiography thyroid scans in retrosternal goiter may occur when (19), radionuclide (20), transmission com there is too little uptake of radioiodine by the goiter puted tomography (21), as well as invasive techniques (10,23). Furthermore, accumulation of these isotopes such as angiography and mediastinoscopic biopsy. The in an intrathoracic location is not specific for goiter as routine chest x-ray is a valuable initial study for com [99mTc]pertechnetate uptake has been reported in sub partmental localization of a mediastinal mass and also sternal parathyroid adenoma (24) and also in an ante demonstrates tracheal displacement or compression nor mediastinal thymoma (25). Iodine-131 mediastinal and areas of calcification. Computerized tomography uptake has also been noted in two cases of bronchi of intrathoracic goiter can note continuity of the me ogenic (26,27). However, in the present case diastinal mass with the cervical gland, well-defined bor the clinical features in combination with high thyroid ders, focal calcifications, high contrast attenuation val hormone levels and isotopic uptake in the intrathoracic ues of the goiter and postcontrast enhancement. goiter with near-total suppression ofthe cervical thyroid Radionuclide scintigraphy is capable of detecting were diagnostic of a toxic intrathoracic goiter. most intrathoracic goiters (6,22) and 1311scanning has Scintigraphy provides an excellent estimate of the been recommended in all mediastinal masses regardless functional status of a mediastinal goiter. The majority of their location (13). The 1311scan is preferred over of such goiters are nontoxic nodules, with the rare case other radioisotopes for demonstration of intrathoracic being associated with hyperthyroidism. Autonomous goiter. The low-energy photons of 1231are absorbed by nodules produce hyperthyroidism when the secretory the thoracic bony structures overlying the goiter, and activity exceeds levels necessary to suppress TSH re

@ Volume 27 e Number 9 September1986 1425 lease; thus the completeness ofsuppression of extranod REFERENCES ular tissue on a thyroid scan is a valuable index of their secretory activity (28). Our case presumably presented 1. Daniel RA Jr., Diveley WL, Edwards WH, et al: Mediastinal tumors. Ann Surg 151: 783—795,1960 early in the development of hyperthyroidism in the 2. Benjamin SP, McCormack Ii, Effler DB, et al: Pri intrathoracic goiter which had not yet produced com mary tumors of the mediastinum. Chest 62:297—303, plete feedback suppression ofthe cervical thyroid. How 1972 ever, the possibility oflow degree autonomous function 3. Sweet RH: Intrathoracic goiter located in the posterior in the cervical thyroid also contributing to the hyper mediastinum. Surg GynecolObstet 89:57—66,1949 4. Lamke LO, Bergdahl L, Lamke B: Intrathoracic : thyroid state cannot be ruled out. A review of 29 cases. Acta Chir Scand 145:83—86, Intrathoracic goiters are generally considered an in 1979 dication for (5), especially in hyperthyroidism, 5. Allo MD, Thompson NW: Rationale for the operative as radioiodine rarely relieves tracheal deviation or management of substernal goiters. Surgery 94:967— compression even though the hyperthyroid state may 977, 1983 6. Falor WH, Kelley TR, Krabill WS: Intrathoracic goi be controlled (29). However, this patient did not have ter.Ann Surg142:238—247,1955 significant tracheal deviation or compression symptoms 7. Dundas P: Intrathoracic aberrant goiter. Acta Chir and was treated with radioiodine after stabilization with Scand 128:729—736,1964 antithyroid drugs. Serial follow-up over 4 mo has shown 8. Katlick MR. Wang C, Grillo HC: Substernal goiter. Ann ThoracSurg39:391—399,1985 definite clinical and biochemical improvement. 9. Calibration and standardization ofthyroid radioiodine Diffuse and nodular toxic goiters account for more uptake measurements. Recommendations drawn up than 90% of the hyperthyroidism seen in practice. The at a consultants meeting 1960, convened by the Inter less common causes ofhyperthyroidism include struma national Atomic Energy Agency. Acta Radiol 58:233— ovarii (30), metastatic well-differentiated 240, 1962 (31 ), subacute (32), and overproduction of 10. Sand ME, Laws HL, McElvein RB: Substernal and intrathoracic goiter: Reconsideration of surgical ap a thyroid stimulating hormone (33). The possibility of proach.Am Surg49:196—202,1983 hyperthyroidism due to should be consid 11. Frazer RG, Pare JAP, eds: Diseases of the medias ered whenever ascites or a palpable ovarian mass is tinum. In Diagnosis of Diseases of the Chest. Phila noted in association with hyperthyroidism. A cervical delphia, WB Saunders, 1978, pp 1793—1870 multinodular goiter is usually present. The diagnosis 12. Kaplan WD, Watnick M, Holman BL: Scintigraphic identification ofcomplete thoracic goiter with normal can be confirmed by showing radioactive iodine uptake appearing cervical thyroid: A case report. J Can Assoc (RAIU) over the pelvic mass. Suppression of thyroid Radiol25:193—195,1974 RAIU may not necessarily occur since hyperplastic 13. Irwin RS, Braman SS, Arvantidis AN, et al: 311thyroid tissue is frequently present in both the cervical and scanning in preoperative diagnosis of mediastinal tu pelvic areas (33). Metastatic papillofollicular cancer is mor. Ann Intern Med 89:73—74,1978 14. Wakeley CPG, Mulvany JH: Intrathoracic goiter. Surg also clinically obvious since most patients have had GynecolObstet70:702—710,1940 previous thyroid surgery for cancer and have extensive 15. Sy WM, Lao RS, Seo IS: Scintigraphic features of metastases to bone, lung, and liver. 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1426 Prakash,Lakshmipathi,Jenaetal TheJournalof NuclearMedicine 24. Naunheim KS, Kaplan EL, Kirchner PT: Preoperative 29. Beierwaltes WH: The treatment of hyperthyroidism technetium-99m imaging of a substernal parathyroid withiodine-l31.Semin NuclMed 8:95—103,1978 adenoma.JNuclMed23:51 1—513,1982 30. Kempers RD, Dockerty MB, Hoffman DL, et al: 25. Wilson RL, Cowan Ri: Tc-99m pertechnetate uptake Struma ovarii—ascitic, hyperthryoid, and asympto in a thymoma: Case report. C/in NuclMed7:149—l50, matic syndromes. Ann Intern Med 72:883—893,1970 1982 31. Chapman CN, Sziklas JJ, Spencer RP, et al: Hyper 26. Fernandez-Ulloa M, Maxon HR. Mehta S: Iodine-131 thyroidism with metastatic follicular thyroid carci uptake by primary lung adenocarcinoma—misinter noma. JNuclMed25:466—468, 1984 pretation of 131jscan. JAMA 236:857—858,1976 32. Teixeira VL, Romaldini JH, Rodrigues HF, et al: 27. Acosta J, Chitkara R, Khan F, et al: Radioactive iodine Thyroid function during the spontaneous course of uptake by a large cell undifferentiated bronchiogenic subacute thyroiditis. J Nucl Med 26:457—460,1985 carcinoma. C/in Nucl Med 7:368—369,1982 33. Hamilton CR, Maloof F: Unusual types of hyperthy 28. Hamburger JI: Solitary autonomously functioning roidism.Medicine52:l95—215,1973 thyroid lesions; Diagnosis, clinical features and path 34. Dorfman SG: Hyperthyroidism: Usual and unusual ogenetic considerations. Am J Med 58:740—748,1975 causes.ArchInternMed 137:995—996,1977

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