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Thyroid Heterotopia as a Rare Cause of Intrapericardial Tumoral Mass
Thyroid Heterotopia as a Rare Cause of Intrapericardial Tumoral Mass: Case Report and Review of the Literature Alison E. Lewis, BSc, and Virginia M. Walley, MD Anatomical Pathology, Department of Laboratory Medicine, University of Ottawa Heart Institute, and Ottawa Civic Hospital, Ottawa, Ontario, Canada
11 This article describes the interesting discovery of a large tumoral mass formed of heterotopic thyroid tissue inside the pericardial cavity of an elderly man who died of unrelated causes. Heterotopic thyroid tissue may be found in many locations throughout the body. Intracardiac and intrapericardial locations, however, are exceptionally rare—this is only the second report of intrapericardial thyroid heterotopia. Such cases may be explained by the proximity of the developing cardiac structures and the foregut, the latter containing thyroid primordia during early embryogenesis. Cardiovasc Pathol 1998;7:173–176 © 1998 by Elsevier Science Inc.
A number of forms of heterotopia may affect the cardiac and pericardial tissues (1). These include germ cell tumors, bronchogenic cysts, rests that form cystic tumors of the atrioventricular node, and heterotopic thymus and thyroid. This report details a case of thyroid heterotopia and reviews the literature relevant to this entity.
Case Report A 93-year-old man with Alzheimer’s dementia was admitted with aspiration pneumonia and died of respiratory failure 27 days later. His past medical history included noninsulin-dependent diabetes mellitus, coronary artery disease, and cerebral transient ischemic attacks. Chest radiographs performed during the patient’s course in hospital demonstrated the pneumonia but were otherwise unremarkable. The patient’s T4, TSH, and thyroglobulin levels were all within normal limits. A full autopsy confirmed the clinical diagnosis of Alzheimer’s disease. Both lungs had marked bronchopneumonia. Generalized and coronary artery atherosclerosis were Manuscript received June 13, 1997; revised August 18, 1997; accepted August 27, 1997. Address for correspondence: Dr. V. M. Walley, Department of Laboratory Medicine, Ottawa Civic Hospital, 1053 Carling Avenue, Ottawa, Ontario, Canada K1Y 4E9; telephone: (613) 761-4245; fax: (613) 761-4403; e-mail:. Cardiovascular Pathology Vol. 7, No. 3, May/June 1998:173–176 1998 by Elsevier Science Inc. All rights reserved. 655 Avenue of the Americas, New York, NY 10010
noted. There was an organizing cerebral infarct in the territory of a thrombosed right middle cerebral artery and status lacunaris. Amyloid, likely so-called “senile systemic” in type, was seen in moderate amounts in the heart. The patient’s thyroid gland was in normal position and of normal size; it was unremarkable except for a focus of fibrosis and dystrophic calcification in the isthmus, measuring 0.8 cm in diameter. An unexpected large round mass was found in the pericardial cavity, adherent to the anterior aspect of the root of the ascending aorta and left lateral pulmonary artery trunk (Figure 1). The mass weighed about 30 g, measured 4.5 3 3.5 3 3.5 cm in greatest diameters, and was covered by a white fibrous, focally calcified, pseudocapsule (Figure 2A). The cut surface of the mass showed a variegated reddishbrown somewhat gelatinous interior with small cystic spaces (Figure 2B). Histology revealed that the mass was entirely composed of benign thyroid tissue including variably sized well-differentiated follicles containing colloid (Figure 2C); there were many areas showing various degenerative changes that included fibrosis and dystrophic calcification. In none of the multiple sections taken was there evidence of teratoma.
Discussion Heterotopic thyroid tissue may be found in many locations; the most common of these are points along the course of the embryonic thyroglossal duct—i.e., at the base of the
1054-8807/98/$19.00 PII S1054-8807(97)00080-X
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Figure 1. This gross photograph at autopsy shows the parietal pericardium opened anteriorly and retracted. The intrapericardial heterotopic thyroid mass (between arrows) is seen adherent to pulmonary artery (Pul 5 pulmonary artery trunk, RV 5 right ventricle; ruler 5 1 cm).
tongue or in the neck. However, heterotopic thyroid tissue has been described in a variety of other locations, including: the trachea; adherent to the esophagus; in the esophagus; elsewhere in the mediastinum; in the right carotid triangle, sella turcica, submucosa of the duodenum, and liver; in a cystic adrenal mass; in other locations in the abdomen; and in the vaginal wall (2). There have also been a number of reports of thyroid rests involving cardiac and related structures; most of those rests have been located in the right ventricle. Thirteen of the 15 cases of intracardiac thyroid heterotopia reported in the English literature (3–17) have been found in women. When reported, the thyroid function tests of all but one (5) of the patients have been stated to be normal; in the one case, however, the patient was taking amiodarone for an arrythmia, so it is unclear whether the thyroid function test abnormality was actually related to the heterotopia. The thyroid gland itself has been described as normal in the majority of cases in the literature. In one patient, how-
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ever, the gland was described as having features of macrofollicular and microfollicular goiter (8). Occasionally, the thyroid gland has been found to contain one or more small nonfunctioning nodules (3,9,14) but never neoplastic foci. Of the 15 reported cases of intracardiac thyroid heterotopia, 13 have involved the right ventricle. The size of these thyroid masses have ranged from 2 3 2 cm to 9 3 6 3 5 cm (3–15). All except three of these right ventricular tumors were adherent to the interventricular septum (3–6,8–10,12– 14). The others arose from the anterior wall (11), the anterior papillary muscle (7), and an ill-defined location “near the pulmonic valve” (15). Common associated clinical findings have included right bundle branch block and right ventricular outflow obstruction. Ten of the 13 right ventricular cases were unexpected in vivo findings, discovered at echocardiography for the investigation of a systolic ejection murmur, abnormal electrocardiography and symptoms such as dyspnea, palpitations, and syncope; many of these tumors were successfully resected. An additional right ventricular tumor (3) was found incidentally at coronary angioplasty performed for unstable angina. Two other tumors were detected post mortem (14,15). There has also been one report in the literature of a left ventricular outflow tract thyroid heterotopia (16); a 2 3 2 cm mass was found in a 56-year-old woman who presented with a murmur, left axis deviation, left anterior hemiblock, right bundle branch block. Additionally, there has also been one report of a 4 3 5 3 3 cm heterotopic thyroid mass found incidentally in the right atrium of a 51-year-old woman at coronary artery bypass surgery (17). Both of these tumors were subsequently surgically excised. Intrapericardial heterotopic thyroid is said to be common (1,18); however, a careful search has revealed only one previous report of intrapericardial heterotopic thyroid, in the German literature (19). That patient was a 67-year-old woman who had died of peritonitis. The pericardial mass was identified at autopsy. This thyroid rest was attached to the parietal pericardium by a short (6-mm) stalk and lay in contact with the ventral part of the aorta. The mass itself measured 2.5 3 2.8 3 1.6 cm and was described as having a thick calcified capsule of hyaline connective tissue covered by mesothelial cells, with a parenchyma of typical thyroid tissue approaching the appearance of a macrofollicular colloid adenoma. The case of heterotopic thyroid reported here is similar to this last case—in its location and gross appearance. It is unusual, even when compared to all cases of cardiac/pericardial heterotopia, however, because of its size and because it was found in a male. The presence of ectopic thyroid tissue located inside the pericardium may be explained by the proximity of the thyroid anlage and the developing heart in the early embryo. Rogers and Kesten (14) provide an excellent review of the embryology involved in the formation of these two structures as they attempt to explain the pathogenesis of their case of intracardiac thyroid heterotopia. On day 17 of em-
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Figure 2. These gross photographs show (A) the external; and (B) the internal/cut surfaces of the heterotopic thyroid mass (ruler 5 1 cm); (C) is a photomicrograph of the mass formed of benign thyroid tissue (hematoxylin phloxine saffon stain; original magnification 3170).
bryonic development, cells in the splanchnic mesoderm proliferate to form two angiogenic clusters, one on each side of midline. These clusters then canalize forming two endothelial heart tubes. The heart tubes are surrounded by the myocardial mantle, which is open dorsally. The pericardial cavity will develop from the intraembryonic coelomic cavity. At this stage, the thyroid primordium in the floor of the pharynx is in contact with the dorsal aspect of the developing heart. By day 19, the thyroid primordium is actually adherent to the dorsal aspect of the developing heart. On day 20, when the two heart tubes have begun to fuse and the myocardial mantle has closed, the thyroid anlage, now elongated, is still adherent to the heart. The lower portion of the flask-shaped thyroid primordium will become the thyroid gland proper, whereas the neck of the flask will become the thyroglossal duct. Prolonged adherence of the thyroid primordium to the developing heart results in thyroid tissue located more caudally than normal, and failure to adhere is thought to result in a lingual thyroid. Intracardiac thyroid rests seem often to be located in the right ventricle alongside the ventricular septum. This would suggest that a constant part of the cardiac primordia comes
in contact with the migrating thyroid anlagen. This has been proposed to be the bulbis cordis (8). It seems likely that the developmental error resulting in thyroid tissue being located inside the pericardium must be the inclusion of a portion of the thyroid diverticulum of the foregut in the pericardial cavity prior to its closure. The segment of the heart tube located adjacent to the bulbis cordis is the truncus arteriosus. This segment will ultimately form the aorta and pulmonary artery. Therefore, it could be proposed that by a mechanism similar to that which produces intracardiac heterotopic thyroid, contact of the thyroid anlage with the truncus arteriosus may result in thyroid tissue being found adherent to the great vessels inside the pericardial sac. Interestingly, although uncommon in humans, intrapericardial thyroid glands are found frequently in other mammals. In a series of 45 dogs, 29 possessed one or more accessory thyroid glands surrounding the ascending aorta in the pericardial sac (20).
The authors thank C. Morelli for preparing the manuscript and W. A. Stinson for the specimen photography.
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LEWIS AND WALLEY PERICARDIAL THYROID HETEROTOPIA
References 1. Burke A, Virmani R. Heterotopias and tumors originating from ectopic tissues. In: Burke A, Virmani R, eds. Tumors of the Heart and Great Vessels. Washington, DC: Armed Forces Institute of Pathology, 1996; 111–125. 2. Rosai J, Carcangiu ML, DeLellis RA. Thyroid tissue in abnormal locations. In: Rosai J, ed. Tumors of the Thyroid Gland. Washington, DC: Armed Forces Institute of Pathology, 1990;317–326. 3. Maillette S, Paquet E, Carrier L, Leclerc Y, Leung T-K, Takahashi A. Asymptomatic heterotopic thyroid tumour in the right ventricular infundibulum. Can J Cardiol 1994;10:37–40. 4. Shemin RJ, Marsh JD, Schoen FJ. Benign intracardiac thyroid mass causing right ventricular outflow tract obstruction. Am J Cardiol 1985; 56:828–829. 5. Richmond I, Whittaker JS, Deiraniya AK, Hassan R. Intracardiac ectopic thyroid: a case report and review of published literature. Thorax 1990;45:293–294. 6. Kantelip B, Lusson JR, De Riberolles C, Lamaison D, Bailly P. Intracardiac ectopic thyroid. Hum Pathol 1986;17:1293–1296. 7. Ansani L, Percoco G, Zanardi F, Peranzoni P, Gamba G, Antonioli G. Intracardiac thyroid heterotopia. Am Heart J 1993;125:1797–1801. 8. Pollice L, Caruso G. Struma cordis: ectopic thyroid goiter in the right ventricle. Arch Pathol Lab Med 1986;110:452–453. 9. Greco-Lucchina P, Ottino GM, Avonto L, Carini G, Pozzi R, Emanuelli G. Ectopic thyroid remnants within the myocardium: an unusual case of right ventricular mass. Am Heart J 1988;115:195–198. 10. Doria E, Agostoni P, Fiorentini C. Accessory thyroid tissue in the right ventricle. Chest 1989;96:424–425.
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11. Lo H-M, Tseng Y-Z, Tseng C-D, Chu S-H, Chuang S-M, Wu T-L. Intracardiac goiter: a cause of right ventricular outflow obstruction and successful operative therapy. Am J Cardiol 1984;53:976–978. 12. Polvani GL, Antona C, Porqueddu M et al. Intracardiac ectopic thyroid: conservative surgical treatment. Ann Thorac Surg 1993;55:1249–1251. 13. Grigg LE, Downey W, Tatoulis J, Hunt D. Benign congenital intracardiac thyroid and polycystic tumor causing right ventricular outflow tract obstruction and conduction disturbance. J Am Coll Cardiol 1987; 9: 225–227. 14. Rogers WM, Kesten HD. A thyroid mass in the ventricular septum obstructing the right ventricular outflow tract and producing a murmer. J Cardiovasc Surg 1963;4:175–180. 15. Dosch R. Uber einen fall von glandula thyroidea accessoria intracardialis. Bietr Pathol Anat 1941;105:244–251. 16. Kon ND, Headley RN, Cordell AR. Successful operative management of struma cordis obstructing the left ventricular outflow tract. Ann Thorac Surg 1988;46:244–245. 17. Rose AG, Novitzky D, Price SK. Heterotopic thyroid tissue in the heart. Am J Cardiovasc Pathol 1988;1:401–404. 18. McAllister HA, Jr., Fenoglio JJ, Jr. Other benign cardiac tumors. In: McAllister HA, Jr., Fenoglio JJ, Jr., eds. Tumors of the Cardiovascular System. Washington, DC: Armed Forces Institute of Pathology, 1978; 68–71. 19. Odstreil B. Ein fall von glandula thryeoidea accessoria pericardialis. Zentralbl Allg Pathol 1942;80:149–152. 20. Kameda Y. The accessory thyroid glands of the dog around the intrapericardial aorta. Arch Histol Jpn 1972;34:375–391.
11 This article describes the interesting discovery of a large tumoral mass formed of heterotopic thyroid tissue inside the pericardial cavity of an elderly man who died of unrelated causes. Heterotopic thyroid tissue may be found in many locations throughout the body. Intracardiac and intrapericardial locations, however, are exceptionally rare—this is only the second report of intrapericardial thyroid heterotopia. Such cases may be explained by the proximity of the developing cardiac structures and the foregut, the latter containing thyroid primordia during early embryogenesis. Cardiovasc Pathol 1998;7:173–176 © 1998 by Elsevier Science Inc.
A number of forms of heterotopia may affect the cardiac and pericardial tissues (1). These include germ cell tumors, bronchogenic cysts, rests that form cystic tumors of the atrioventricular node, and heterotopic thymus and thyroid. This report details a case of thyroid heterotopia and reviews the literature relevant to this entity.
Case Report A 93-year-old man with Alzheimer’s dementia was admitted with aspiration pneumonia and died of respiratory failure 27 days later. His past medical history included noninsulin-dependent diabetes mellitus, coronary artery disease, and cerebral transient ischemic attacks. Chest radiographs performed during the patient’s course in hospital demonstrated the pneumonia but were otherwise unremarkable. The patient’s T4, TSH, and thyroglobulin levels were all within normal limits. A full autopsy confirmed the clinical diagnosis of Alzheimer’s disease. Both lungs had marked bronchopneumonia. Generalized and coronary artery atherosclerosis were Manuscript received June 13, 1997; revised August 18, 1997; accepted August 27, 1997. Address for correspondence: Dr. V. M. Walley, Department of Laboratory Medicine, Ottawa Civic Hospital, 1053 Carling Avenue, Ottawa, Ontario, Canada K1Y 4E9; telephone: (613) 761-4245; fax: (613) 761-4403; e-mail:
noted. There was an organizing cerebral infarct in the territory of a thrombosed right middle cerebral artery and status lacunaris. Amyloid, likely so-called “senile systemic” in type, was seen in moderate amounts in the heart. The patient’s thyroid gland was in normal position and of normal size; it was unremarkable except for a focus of fibrosis and dystrophic calcification in the isthmus, measuring 0.8 cm in diameter. An unexpected large round mass was found in the pericardial cavity, adherent to the anterior aspect of the root of the ascending aorta and left lateral pulmonary artery trunk (Figure 1). The mass weighed about 30 g, measured 4.5 3 3.5 3 3.5 cm in greatest diameters, and was covered by a white fibrous, focally calcified, pseudocapsule (Figure 2A). The cut surface of the mass showed a variegated reddishbrown somewhat gelatinous interior with small cystic spaces (Figure 2B). Histology revealed that the mass was entirely composed of benign thyroid tissue including variably sized well-differentiated follicles containing colloid (Figure 2C); there were many areas showing various degenerative changes that included fibrosis and dystrophic calcification. In none of the multiple sections taken was there evidence of teratoma.
Discussion Heterotopic thyroid tissue may be found in many locations; the most common of these are points along the course of the embryonic thyroglossal duct—i.e., at the base of the
1054-8807/98/$19.00 PII S1054-8807(97)00080-X
174
LEWIS AND WALLEY PERICARDIAL THYROID HETEROTOPIA
Figure 1. This gross photograph at autopsy shows the parietal pericardium opened anteriorly and retracted. The intrapericardial heterotopic thyroid mass (between arrows) is seen adherent to pulmonary artery (Pul 5 pulmonary artery trunk, RV 5 right ventricle; ruler 5 1 cm).
tongue or in the neck. However, heterotopic thyroid tissue has been described in a variety of other locations, including: the trachea; adherent to the esophagus; in the esophagus; elsewhere in the mediastinum; in the right carotid triangle, sella turcica, submucosa of the duodenum, and liver; in a cystic adrenal mass; in other locations in the abdomen; and in the vaginal wall (2). There have also been a number of reports of thyroid rests involving cardiac and related structures; most of those rests have been located in the right ventricle. Thirteen of the 15 cases of intracardiac thyroid heterotopia reported in the English literature (3–17) have been found in women. When reported, the thyroid function tests of all but one (5) of the patients have been stated to be normal; in the one case, however, the patient was taking amiodarone for an arrythmia, so it is unclear whether the thyroid function test abnormality was actually related to the heterotopia. The thyroid gland itself has been described as normal in the majority of cases in the literature. In one patient, how-
Cardiovasc Pathol Vol. 7, No. 3 May/June 1998:173–176
ever, the gland was described as having features of macrofollicular and microfollicular goiter (8). Occasionally, the thyroid gland has been found to contain one or more small nonfunctioning nodules (3,9,14) but never neoplastic foci. Of the 15 reported cases of intracardiac thyroid heterotopia, 13 have involved the right ventricle. The size of these thyroid masses have ranged from 2 3 2 cm to 9 3 6 3 5 cm (3–15). All except three of these right ventricular tumors were adherent to the interventricular septum (3–6,8–10,12– 14). The others arose from the anterior wall (11), the anterior papillary muscle (7), and an ill-defined location “near the pulmonic valve” (15). Common associated clinical findings have included right bundle branch block and right ventricular outflow obstruction. Ten of the 13 right ventricular cases were unexpected in vivo findings, discovered at echocardiography for the investigation of a systolic ejection murmur, abnormal electrocardiography and symptoms such as dyspnea, palpitations, and syncope; many of these tumors were successfully resected. An additional right ventricular tumor (3) was found incidentally at coronary angioplasty performed for unstable angina. Two other tumors were detected post mortem (14,15). There has also been one report in the literature of a left ventricular outflow tract thyroid heterotopia (16); a 2 3 2 cm mass was found in a 56-year-old woman who presented with a murmur, left axis deviation, left anterior hemiblock, right bundle branch block. Additionally, there has also been one report of a 4 3 5 3 3 cm heterotopic thyroid mass found incidentally in the right atrium of a 51-year-old woman at coronary artery bypass surgery (17). Both of these tumors were subsequently surgically excised. Intrapericardial heterotopic thyroid is said to be common (1,18); however, a careful search has revealed only one previous report of intrapericardial heterotopic thyroid, in the German literature (19). That patient was a 67-year-old woman who had died of peritonitis. The pericardial mass was identified at autopsy. This thyroid rest was attached to the parietal pericardium by a short (6-mm) stalk and lay in contact with the ventral part of the aorta. The mass itself measured 2.5 3 2.8 3 1.6 cm and was described as having a thick calcified capsule of hyaline connective tissue covered by mesothelial cells, with a parenchyma of typical thyroid tissue approaching the appearance of a macrofollicular colloid adenoma. The case of heterotopic thyroid reported here is similar to this last case—in its location and gross appearance. It is unusual, even when compared to all cases of cardiac/pericardial heterotopia, however, because of its size and because it was found in a male. The presence of ectopic thyroid tissue located inside the pericardium may be explained by the proximity of the thyroid anlage and the developing heart in the early embryo. Rogers and Kesten (14) provide an excellent review of the embryology involved in the formation of these two structures as they attempt to explain the pathogenesis of their case of intracardiac thyroid heterotopia. On day 17 of em-
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Figure 2. These gross photographs show (A) the external; and (B) the internal/cut surfaces of the heterotopic thyroid mass (ruler 5 1 cm); (C) is a photomicrograph of the mass formed of benign thyroid tissue (hematoxylin phloxine saffon stain; original magnification 3170).
bryonic development, cells in the splanchnic mesoderm proliferate to form two angiogenic clusters, one on each side of midline. These clusters then canalize forming two endothelial heart tubes. The heart tubes are surrounded by the myocardial mantle, which is open dorsally. The pericardial cavity will develop from the intraembryonic coelomic cavity. At this stage, the thyroid primordium in the floor of the pharynx is in contact with the dorsal aspect of the developing heart. By day 19, the thyroid primordium is actually adherent to the dorsal aspect of the developing heart. On day 20, when the two heart tubes have begun to fuse and the myocardial mantle has closed, the thyroid anlage, now elongated, is still adherent to the heart. The lower portion of the flask-shaped thyroid primordium will become the thyroid gland proper, whereas the neck of the flask will become the thyroglossal duct. Prolonged adherence of the thyroid primordium to the developing heart results in thyroid tissue located more caudally than normal, and failure to adhere is thought to result in a lingual thyroid. Intracardiac thyroid rests seem often to be located in the right ventricle alongside the ventricular septum. This would suggest that a constant part of the cardiac primordia comes
in contact with the migrating thyroid anlagen. This has been proposed to be the bulbis cordis (8). It seems likely that the developmental error resulting in thyroid tissue being located inside the pericardium must be the inclusion of a portion of the thyroid diverticulum of the foregut in the pericardial cavity prior to its closure. The segment of the heart tube located adjacent to the bulbis cordis is the truncus arteriosus. This segment will ultimately form the aorta and pulmonary artery. Therefore, it could be proposed that by a mechanism similar to that which produces intracardiac heterotopic thyroid, contact of the thyroid anlage with the truncus arteriosus may result in thyroid tissue being found adherent to the great vessels inside the pericardial sac. Interestingly, although uncommon in humans, intrapericardial thyroid glands are found frequently in other mammals. In a series of 45 dogs, 29 possessed one or more accessory thyroid glands surrounding the ascending aorta in the pericardial sac (20).
The authors thank C. Morelli for preparing the manuscript and W. A. Stinson for the specimen photography.
176
LEWIS AND WALLEY PERICARDIAL THYROID HETEROTOPIA
References 1. Burke A, Virmani R. Heterotopias and tumors originating from ectopic tissues. In: Burke A, Virmani R, eds. Tumors of the Heart and Great Vessels. Washington, DC: Armed Forces Institute of Pathology, 1996; 111–125. 2. Rosai J, Carcangiu ML, DeLellis RA. Thyroid tissue in abnormal locations. In: Rosai J, ed. Tumors of the Thyroid Gland. Washington, DC: Armed Forces Institute of Pathology, 1990;317–326. 3. Maillette S, Paquet E, Carrier L, Leclerc Y, Leung T-K, Takahashi A. Asymptomatic heterotopic thyroid tumour in the right ventricular infundibulum. Can J Cardiol 1994;10:37–40. 4. Shemin RJ, Marsh JD, Schoen FJ. Benign intracardiac thyroid mass causing right ventricular outflow tract obstruction. Am J Cardiol 1985; 56:828–829. 5. Richmond I, Whittaker JS, Deiraniya AK, Hassan R. Intracardiac ectopic thyroid: a case report and review of published literature. Thorax 1990;45:293–294. 6. Kantelip B, Lusson JR, De Riberolles C, Lamaison D, Bailly P. Intracardiac ectopic thyroid. Hum Pathol 1986;17:1293–1296. 7. Ansani L, Percoco G, Zanardi F, Peranzoni P, Gamba G, Antonioli G. Intracardiac thyroid heterotopia. Am Heart J 1993;125:1797–1801. 8. Pollice L, Caruso G. Struma cordis: ectopic thyroid goiter in the right ventricle. Arch Pathol Lab Med 1986;110:452–453. 9. Greco-Lucchina P, Ottino GM, Avonto L, Carini G, Pozzi R, Emanuelli G. Ectopic thyroid remnants within the myocardium: an unusual case of right ventricular mass. Am Heart J 1988;115:195–198. 10. Doria E, Agostoni P, Fiorentini C. Accessory thyroid tissue in the right ventricle. Chest 1989;96:424–425.
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11. Lo H-M, Tseng Y-Z, Tseng C-D, Chu S-H, Chuang S-M, Wu T-L. Intracardiac goiter: a cause of right ventricular outflow obstruction and successful operative therapy. Am J Cardiol 1984;53:976–978. 12. Polvani GL, Antona C, Porqueddu M et al. Intracardiac ectopic thyroid: conservative surgical treatment. Ann Thorac Surg 1993;55:1249–1251. 13. Grigg LE, Downey W, Tatoulis J, Hunt D. Benign congenital intracardiac thyroid and polycystic tumor causing right ventricular outflow tract obstruction and conduction disturbance. J Am Coll Cardiol 1987; 9: 225–227. 14. Rogers WM, Kesten HD. A thyroid mass in the ventricular septum obstructing the right ventricular outflow tract and producing a murmer. J Cardiovasc Surg 1963;4:175–180. 15. Dosch R. Uber einen fall von glandula thyroidea accessoria intracardialis. Bietr Pathol Anat 1941;105:244–251. 16. Kon ND, Headley RN, Cordell AR. Successful operative management of struma cordis obstructing the left ventricular outflow tract. Ann Thorac Surg 1988;46:244–245. 17. Rose AG, Novitzky D, Price SK. Heterotopic thyroid tissue in the heart. Am J Cardiovasc Pathol 1988;1:401–404. 18. McAllister HA, Jr., Fenoglio JJ, Jr. Other benign cardiac tumors. In: McAllister HA, Jr., Fenoglio JJ, Jr., eds. Tumors of the Cardiovascular System. Washington, DC: Armed Forces Institute of Pathology, 1978; 68–71. 19. Odstreil B. Ein fall von glandula thryeoidea accessoria pericardialis. Zentralbl Allg Pathol 1942;80:149–152. 20. Kameda Y. The accessory thyroid glands of the dog around the intrapericardial aorta. Arch Histol Jpn 1972;34:375–391.