: Case Report and Review of the Literature
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Michael J. Connolly, MD, Dorothy Lazinski, MD, FRCPC, Katherine A. Aoki, MD, Laurie McLean, MD, FRCSC, Carlos Torres, MD, Marlise P. dos Santos, MD, MPH, MSc, FRCPC First Published January 28, 2019 Case Report
https://doi.org/10.1177/0145561318822933
Article information
Free Access
Article Information
Article first published online: January 28, 2019
Michael J. Connolly, MD1, Dorothy Lazinski, MD, FRCPC2, Katherine A. Aoki, MD3, Laurie McLean, MD, FRCSC4, 5, Carlos Torres, MD1, 5, Marlise P. dos Santos, MD, MPH, MSc, FRCPC1, 5
1Department of Medical Imaging, The Ottawa Hospital, University of Ottawa, Ottawa, Ontario, Canada
2Joint Department of Medical Imaging, University of Toronto, Toronto, Ontario, Canada
3Department of Family Medicine, University of Ottawa, Ottawa, Ontario, Canada
4Department of Otolaryngology, Head and Neck Surgery, The Ottawa Hospital, University of Ottawa, Ottawa, Ontario, Canada
5Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
Corresponding Author: Marlise P. dos Santos, MD, MPH, MSc, FRCPC, The Ottawa Hospital Civic Campus, Department of Medical Imaging, Mailbox 232—Office# 01-1-10-A, 1053 Carling Avenue, Ottawa, Ontario, Canada K1Y 4E9. Email: msantos@toh.ca
Abstract
During routine blood work, a 53-year-old female patient was noted to have asymptomatic hypercalcemia and subsequently found to have hyperparathyroidism. Localization studies for a suspected parathyroid adenoma included 99mTc Sestamibi scintigraphy, Single Photon Emission Computed Tomography (SPECT)/computed tomography (CT) study, and ultrasound of the neck, which were initially read as negative for parathyroid adenoma. A contrast-enhanced CT scan of the neck was performed to locate the suspected parathyroid adenoma and demonstrated a soft tissue lesion within the right piriform sinus. Flexible fiber optic nasolaryngoscopy revealed a submucosal lesion in the right piriform sinus. Following these findings, the initial 99mTc Sestamibi scintigraphy and SPECT/CT were reviewed with confirmation of a focal area of increased activity superior to the right thyroid lobe, corresponding to a nodule in the right piriform sinus that demonstrated increased activity on SPECT/CT. The patient was brought to the operating room for surgical management where a laryngoscope and operating microscope were utilized. The encapsulated lesion was dissected and excised in total. The parathyroid hormone and ionized calcium levels normalized postoperatively. Pathology confirmed a parathyroid adenoma. Parathyroid adenomas are the most common cause of primary hyperparathyroidism. Sixteen percent of parathyroid adenomas can be situated in an ectopic location. Ectopic parathyroid adenomas in the piriform sinus are rare with only a few previously documented cases. We document a rare case of ectopic parathyroid adenoma in the piriform sinus overlooked on initial imaging studies. These lesions can be challenging to localize, however, an understanding of embryology, close scrutiny of possible ectopic locations, and the application of complementary imaging techniques may prove useful for surgeons and clinicians.
Keywords Parathyroid neoplasms, Hormones, Ectopic, Parathyroid Glands, Hyperparathyroidism
Introduction
Primary hyperparathyroidism (PH) is caused by overactivity of the parathyroid gland (PG) leading to increased parathyroid hormone (PTH) levels and hypercalcemia. Ninety percent of PH cases are caused by a single parathyroid adenoma with less common causes including multiple gland hyperplasia (6%), double adenomas (4%), and parathyroid cancer (<1%).1 In a study of 231 patients who underwent surgery for PH, 37 (16%) had PGs in ectopic locations.2 It is important to be aware of this anatomic occurrence and the influence on appropriate imaging modalities for detection and surgical treatment.
Case Report
This case report was approved by the Ottawa Health Sciences Network Research Ethics Board.
During routine blood work at a weight management clinic, a 53-year-old female patient was noted to have asymptomatic hypercalcemia (serum calcium 2.64 mmol/L [normal: 2.12-2.52 mmol/L], albumin 39 g/L [normal: 34-46 g/L]), with subsequent serum PTH noted to be elevated (22.8 pmol/L [normal: 1.6-9.3 pmol/L]). Further elicitation of history revealed mild polyuria/polydipsia, occasional constipation, and fatigue but no cognitive issues, osteoporosis, bone pain, or renal calculi.
Bone mineral densitometry was normal. Localization studies included 99mTc Sestamibi scintigraphy and Single Photon Emission Computed Tomography (SPECT)/CT study (Figure 1A-C), which were initially read as negative for parathyroid adenoma, and an ultrasound of the neck which revealed a multinodular thyroid goiter without visualization of a parathyroid adenoma. A contrast-enhanced CT scan (CE-CT) of the neck was performed to try and help locate a suspected parathyroid adenoma. The CT scan demonstrated a well-defined, enhancing, noninvasive, soft tissue mass lesion within the right piriform sinus measuring 7 mm anteroposterior × 11 mm transverse × 11 mm craniocaudal (Figure 1D).
Figure 1. (A) 99mTc-Sestamibi scintigraphy demonstrating increased uptake on early acquisition, (B) subtle persistance on 2-hour delayed acquisition. (C) 99mTc-Sestamibi Single Photon Emission Computed Tomography (SPECT)/CT, focal increased activity in right piriform sinus, and (D) CE-CT, hyperenhancing lesion in right piriform sinus. CT indicates computed tomography; CE-CT, contrast-enhanced CT.
The patient was referred to otolaryngology for surgical evaluation and management. Flexible fiber optic nasolaryngoscopy revealed a smooth, nonulcerated, tan colored submucosal lesion in the right piriform sinus. Following this finding and the CE-CT scan findings, the initial 99mTc Sestamibi scintigraphy and SPECT/CT were reviewed and indeed there was a focal area of increased activity superior to the right thyroid lobe (Figure 1A and B), corresponding to a soft tissue nodule in the right piriform sinus (Figure 1C) that demonstrated increased activity on SPECT/CT.
The patient was brought to the operating room, intubated, and placed under general anesthetic. A Kleinsasser laryngoscope was suspended. The operating microscope was utilized. The lesion could easily be identified immediately submucosal in the right piriform fossa (Figure 2). Using the microlaryngeal scissors, a small 5 mm incision was made in the submucosa overlying the lesion. The encapsulated lesion was easily dissected free using blunt dissection (microlaryngeal spatula) and excised in total with no evidence of tumor spillage or capsular violation. The PTH level postoperatively was 1.0 pmol/L (pre-op: 22.8 pmol/L) with ionized calcium level of 1.28 mmol/L (normal: 1.15-1.32 mmol/L). Pathology confirmed a parathyroid adenoma (Figure 3).
Figure 2. Magnified view of the piriform fossa through rigid laryngoscope demonstrating a smooth and nonulcerated nodular lesion immediately below the normal mucosa.
Figure 3. Pathological sections of parathyroid adenoma (hematoxylin and eosin stain). Low power: adenoma with lobulated appearance surrounded by thin fibrous capsule. Compressed atrophic parathyroid tissue at periphery (*). High power (inset): neoplastic cells with clear cytoplasm and uniform nuclei without significant atypia.
Postoperatively, the patient remained NPO for 72 hours to encourage wound healing by secondary intention and help decrease the risk of a leak. The patient also received perioperative antibiotics. On postoperative day 3, the patient underwent a Gastrografin swallow study, which was normal. The patient then resumed normal oral intake.
The patient otherwise recovered well with normalization and stability of biochemical tests at 2 weeks postresection (ionized calcium: 1.04 mmol/L, serum PTH 8.6 pmol/L) and 2 years post resection (ionized calcium: 1.07 mmol/L).
Discussion
There are usually 4 PGs, which are paired superiorly and inferiorly in close anatomical relationship to the thyroid gland. Embryologically, the PGs originate from the third and fourth branchial pouches. The upper pair of glands arise from the fourth branchial pouch and are usually located in proximity to the dorsum of the upper thyroid lobes due to their shared origin. Ectopic superior PGs have previously been defined as being in a location other than juxtacricothyroidal posteriorly or within the capsule of the posterior surface of the superior pole of the thyroid gland.2,3 In addition to the upper pair of glands and thyroid, the fourth branchial pouch gives rise to the apex of piriform sinus, which gives an embryological explanation for the ectopic position in this case.4,5 Ectopic parathyroid adenoma in the piriform sinus is rare, with only a few, previously documented cases found on in the medical literature.6–8
Preoperative imaging for PH relies primarily on ultrasound and 99mTc Sestamibi scintigraphy. The typical sonographic appearance of a parathyroid adenoma is that of an oval-shaped hypoechoic lesion found in close relation to the thyroid gland. Doppler imaging can show a feeding vessel at one of the poles with characteristic arc or rim of peripheral vascularity.9,10 Ectopic parathyroid adenomas can be missed on ultrasound due to operator technique, interpretation, or technical factors, such as lack of acoustic window. On a meta-analysis, the pooled sensitivity and the positive predictive value for parathyroid adenoma on ultrasound are 76.1% and 93.2%, respectively.11 Fused SPECT/CT coregisters the increased radiotracer activity with anatomic structures. 99mTc Sestamibi-SPECT has pooled sensitivity and Positive Predictive Value (PPV) of 78.9% and 90.7%, respectively.11 SPECT/CT doesn’t have any clinical value over conventional SPECT for eutopic PGs but has value in resolving the aberrant anatomic location of an ectopic PG.12 We believe that the rare ectopic location in this case led to the missed finding on the initial 99mTc-Sestamibi scintigraphy and SPECT/CT imaging.
Contrast-enhanced CT and magnetic resonance imaging may be more beneficial in the setting of failed parathyroidectomy or if there is suspicion of an ectopic parathyroid adenoma. Contrast-enhanced CT can detect parathyroid adenoma based on their predictable locations, hyperenhancement (as compared to lymph nodes), and size (mean: 11.4 mm, range: 5-26 mm).13 The differential for the imaging appearance of a parathyroid adenoma includes lymph node, parathyroid hyperplasia, and exophytic thyroid nodule. Variations in CT imaging technique include the 4-dimensional CT (multiphase study assessing for changes in perfusion of contrast) which exploits the early enhancement of parathyroid adenomas with a reported sensitivity and PPV of 89.4% and 93.5%,11 respectively.
In conclusion, ectopic parathyroid adenomas are not an uncommon cause of PH. With only a few cases of ectopic parathyroid adenomas in the piriform sinus previously documented, we present a case that was overlooked on initial imaging studies due to the rare location. These lesions can be challenging to localize; however, an understanding of embryology, close scrutiny of possible ectopic locations, and the application of complementary imaging techniques may prove useful for surgeons and clinicians.
Acknowledgments
The authors would like to thank Dr M. Pelletier-Galarneau from the Department of Nuclear Medicine and Dr K. T. Mai from the Department of Pathology at The Ottawa Hospital/University of Ottawa, Ottawa, Canada, for their contributions.
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.
References
1. Ruda, JM, Hollenbeak, C, Stack, BC. A systematic review of the diagnosis and treatment of primary hyperparathyroidism from 1995 to 2003. Otolaryngol Head Neck Surg. 2005;132(3):359–372.
Google Scholar | SAGE Journals
2. Phitayakorn, R, McHenry, CR. Incidence and location of ectopic abnormal parathyroid glands. Am J Surg. 2006;191(3):418–423.
Google Scholar | Crossref
3. Wang, C . The anatomic basis of parathyroid surgery. Ann Surg. 1976;183(3):271–275.
Google Scholar | Crossref
4. Benson, MT, Dalen, K, Mancuso, AA. Congenital anomalies of the branchial appartus: embryology and pathologic anatomy. Radiographics. 1992;12(5):1175–1189.
Google Scholar | Crossref
5. Miller, DL, Craig, WD, Haines, G. Retropharyngeal parathyroid adenoma: precise preoperative localization with CT and arterial infusion of contrast material. AJR Am J Roentgenol. 1997;169(3):695–696.
Google Scholar | Crossref
6. Guevara, N, Agopian, B, Benisvy, D. Ectopic pyriform sinus parathyroid adenoma. Eur Ann Otorhinolaryngol Head Neck Dis. 2013;130(2):95–98.
Google Scholar | Crossref
7. Dedivitis, RA, Guimarães, AV, Pontes, GB. Multiple ectopic parathyroid adenomas. Sao Paulo Med J. 2004;122(1):32–34.
Google Scholar | Crossref
8. Stojadinovic, A, Shriver, CD, Casler, JD. Endoscopic laser excision of ectopic pyriform sinus parathyroid adenoma. Arch Surg. 1998;133(1):101–103.
Google Scholar | Crossref
9. Johnson, NA, Tublin, ME, Ogilvie, JB. Parathyroid imaging: technique and role in the preoperative evaluation of primary hyperparathyroidism. AJR Am J Roentgenol. 2007;188(6):1706–1715.
Google Scholar | Crossref
10. Rickes, S, Sitzy, J, Neye, H. High resolution ultrasound in combination with colour-doppler sonography for preoperative localization of parathyroid adenomas in patients with primary hyperparathyroidism. Ultraschall Med. 2003;24(2):85–89.
Google Scholar | Crossref
11. Cheung, K, Wang, TS, Farrokhyar, F. A meta-analysis of preoperative localization techniques for patients with primary hyperparathyroidism. Ann Surg Oncol. 2012;19(2):577–583.
Google Scholar | Crossref
12. Gayed, IW, Kim, EE, Broussard, WF. The value of 99mTc-sestamibi SPECT/CT over conventional SPECT in the evaluation of parathyroid adenomas or hyperplasia. J Nucl Med. 2005;46(2):248–252.
Google Scholar
13. Randall, GJ, Zald, PB, Cohen, JI. Contrast-enhanced MDCT characteristics of parathyroid adenomas. AJR Am J Roentgenol. 2009;193(2):W139–W143.
Google Scholar | Crossref
Show less
Michael J. Connolly, MD, Dorothy Lazinski, MD, FRCPC, Katherine A. Aoki, MD, Laurie McLean, MD, FRCSC, Carlos Torres, MD, Marlise P. dos Santos, MD, MPH, MSc, FRCPC First Published January 28, 2019 Case Report
https://doi.org/10.1177/0145561318822933
Article information
Free Access
Article Information
Article first published online: January 28, 2019
Michael J. Connolly, MD1, Dorothy Lazinski, MD, FRCPC2, Katherine A. Aoki, MD3, Laurie McLean, MD, FRCSC4, 5, Carlos Torres, MD1, 5, Marlise P. dos Santos, MD, MPH, MSc, FRCPC1, 5
1Department of Medical Imaging, The Ottawa Hospital, University of Ottawa, Ottawa, Ontario, Canada
2Joint Department of Medical Imaging, University of Toronto, Toronto, Ontario, Canada
3Department of Family Medicine, University of Ottawa, Ottawa, Ontario, Canada
4Department of Otolaryngology, Head and Neck Surgery, The Ottawa Hospital, University of Ottawa, Ottawa, Ontario, Canada
5Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
Corresponding Author: Marlise P. dos Santos, MD, MPH, MSc, FRCPC, The Ottawa Hospital Civic Campus, Department of Medical Imaging, Mailbox 232—Office# 01-1-10-A, 1053 Carling Avenue, Ottawa, Ontario, Canada K1Y 4E9. Email: msantos@toh.ca
Abstract
During routine blood work, a 53-year-old female patient was noted to have asymptomatic hypercalcemia and subsequently found to have hyperparathyroidism. Localization studies for a suspected parathyroid adenoma included 99mTc Sestamibi scintigraphy, Single Photon Emission Computed Tomography (SPECT)/computed tomography (CT) study, and ultrasound of the neck, which were initially read as negative for parathyroid adenoma. A contrast-enhanced CT scan of the neck was performed to locate the suspected parathyroid adenoma and demonstrated a soft tissue lesion within the right piriform sinus. Flexible fiber optic nasolaryngoscopy revealed a submucosal lesion in the right piriform sinus. Following these findings, the initial 99mTc Sestamibi scintigraphy and SPECT/CT were reviewed with confirmation of a focal area of increased activity superior to the right thyroid lobe, corresponding to a nodule in the right piriform sinus that demonstrated increased activity on SPECT/CT. The patient was brought to the operating room for surgical management where a laryngoscope and operating microscope were utilized. The encapsulated lesion was dissected and excised in total. The parathyroid hormone and ionized calcium levels normalized postoperatively. Pathology confirmed a parathyroid adenoma. Parathyroid adenomas are the most common cause of primary hyperparathyroidism. Sixteen percent of parathyroid adenomas can be situated in an ectopic location. Ectopic parathyroid adenomas in the piriform sinus are rare with only a few previously documented cases. We document a rare case of ectopic parathyroid adenoma in the piriform sinus overlooked on initial imaging studies. These lesions can be challenging to localize, however, an understanding of embryology, close scrutiny of possible ectopic locations, and the application of complementary imaging techniques may prove useful for surgeons and clinicians.
Keywords Parathyroid neoplasms, Hormones, Ectopic, Parathyroid Glands, Hyperparathyroidism
Introduction
Primary hyperparathyroidism (PH) is caused by overactivity of the parathyroid gland (PG) leading to increased parathyroid hormone (PTH) levels and hypercalcemia. Ninety percent of PH cases are caused by a single parathyroid adenoma with less common causes including multiple gland hyperplasia (6%), double adenomas (4%), and parathyroid cancer (<1%).1 In a study of 231 patients who underwent surgery for PH, 37 (16%) had PGs in ectopic locations.2 It is important to be aware of this anatomic occurrence and the influence on appropriate imaging modalities for detection and surgical treatment.
Case Report
This case report was approved by the Ottawa Health Sciences Network Research Ethics Board.
During routine blood work at a weight management clinic, a 53-year-old female patient was noted to have asymptomatic hypercalcemia (serum calcium 2.64 mmol/L [normal: 2.12-2.52 mmol/L], albumin 39 g/L [normal: 34-46 g/L]), with subsequent serum PTH noted to be elevated (22.8 pmol/L [normal: 1.6-9.3 pmol/L]). Further elicitation of history revealed mild polyuria/polydipsia, occasional constipation, and fatigue but no cognitive issues, osteoporosis, bone pain, or renal calculi.
Bone mineral densitometry was normal. Localization studies included 99mTc Sestamibi scintigraphy and Single Photon Emission Computed Tomography (SPECT)/CT study (Figure 1A-C), which were initially read as negative for parathyroid adenoma, and an ultrasound of the neck which revealed a multinodular thyroid goiter without visualization of a parathyroid adenoma. A contrast-enhanced CT scan (CE-CT) of the neck was performed to try and help locate a suspected parathyroid adenoma. The CT scan demonstrated a well-defined, enhancing, noninvasive, soft tissue mass lesion within the right piriform sinus measuring 7 mm anteroposterior × 11 mm transverse × 11 mm craniocaudal (Figure 1D).
Figure 1. (A) 99mTc-Sestamibi scintigraphy demonstrating increased uptake on early acquisition, (B) subtle persistance on 2-hour delayed acquisition. (C) 99mTc-Sestamibi Single Photon Emission Computed Tomography (SPECT)/CT, focal increased activity in right piriform sinus, and (D) CE-CT, hyperenhancing lesion in right piriform sinus. CT indicates computed tomography; CE-CT, contrast-enhanced CT.
The patient was referred to otolaryngology for surgical evaluation and management. Flexible fiber optic nasolaryngoscopy revealed a smooth, nonulcerated, tan colored submucosal lesion in the right piriform sinus. Following this finding and the CE-CT scan findings, the initial 99mTc Sestamibi scintigraphy and SPECT/CT were reviewed and indeed there was a focal area of increased activity superior to the right thyroid lobe (Figure 1A and B), corresponding to a soft tissue nodule in the right piriform sinus (Figure 1C) that demonstrated increased activity on SPECT/CT.
The patient was brought to the operating room, intubated, and placed under general anesthetic. A Kleinsasser laryngoscope was suspended. The operating microscope was utilized. The lesion could easily be identified immediately submucosal in the right piriform fossa (Figure 2). Using the microlaryngeal scissors, a small 5 mm incision was made in the submucosa overlying the lesion. The encapsulated lesion was easily dissected free using blunt dissection (microlaryngeal spatula) and excised in total with no evidence of tumor spillage or capsular violation. The PTH level postoperatively was 1.0 pmol/L (pre-op: 22.8 pmol/L) with ionized calcium level of 1.28 mmol/L (normal: 1.15-1.32 mmol/L). Pathology confirmed a parathyroid adenoma (Figure 3).
Figure 2. Magnified view of the piriform fossa through rigid laryngoscope demonstrating a smooth and nonulcerated nodular lesion immediately below the normal mucosa.
Figure 3. Pathological sections of parathyroid adenoma (hematoxylin and eosin stain). Low power: adenoma with lobulated appearance surrounded by thin fibrous capsule. Compressed atrophic parathyroid tissue at periphery (*). High power (inset): neoplastic cells with clear cytoplasm and uniform nuclei without significant atypia.
Postoperatively, the patient remained NPO for 72 hours to encourage wound healing by secondary intention and help decrease the risk of a leak. The patient also received perioperative antibiotics. On postoperative day 3, the patient underwent a Gastrografin swallow study, which was normal. The patient then resumed normal oral intake.
The patient otherwise recovered well with normalization and stability of biochemical tests at 2 weeks postresection (ionized calcium: 1.04 mmol/L, serum PTH 8.6 pmol/L) and 2 years post resection (ionized calcium: 1.07 mmol/L).
Discussion
There are usually 4 PGs, which are paired superiorly and inferiorly in close anatomical relationship to the thyroid gland. Embryologically, the PGs originate from the third and fourth branchial pouches. The upper pair of glands arise from the fourth branchial pouch and are usually located in proximity to the dorsum of the upper thyroid lobes due to their shared origin. Ectopic superior PGs have previously been defined as being in a location other than juxtacricothyroidal posteriorly or within the capsule of the posterior surface of the superior pole of the thyroid gland.2,3 In addition to the upper pair of glands and thyroid, the fourth branchial pouch gives rise to the apex of piriform sinus, which gives an embryological explanation for the ectopic position in this case.4,5 Ectopic parathyroid adenoma in the piriform sinus is rare, with only a few, previously documented cases found on in the medical literature.6–8
Preoperative imaging for PH relies primarily on ultrasound and 99mTc Sestamibi scintigraphy. The typical sonographic appearance of a parathyroid adenoma is that of an oval-shaped hypoechoic lesion found in close relation to the thyroid gland. Doppler imaging can show a feeding vessel at one of the poles with characteristic arc or rim of peripheral vascularity.9,10 Ectopic parathyroid adenomas can be missed on ultrasound due to operator technique, interpretation, or technical factors, such as lack of acoustic window. On a meta-analysis, the pooled sensitivity and the positive predictive value for parathyroid adenoma on ultrasound are 76.1% and 93.2%, respectively.11 Fused SPECT/CT coregisters the increased radiotracer activity with anatomic structures. 99mTc Sestamibi-SPECT has pooled sensitivity and Positive Predictive Value (PPV) of 78.9% and 90.7%, respectively.11 SPECT/CT doesn’t have any clinical value over conventional SPECT for eutopic PGs but has value in resolving the aberrant anatomic location of an ectopic PG.12 We believe that the rare ectopic location in this case led to the missed finding on the initial 99mTc-Sestamibi scintigraphy and SPECT/CT imaging.
Contrast-enhanced CT and magnetic resonance imaging may be more beneficial in the setting of failed parathyroidectomy or if there is suspicion of an ectopic parathyroid adenoma. Contrast-enhanced CT can detect parathyroid adenoma based on their predictable locations, hyperenhancement (as compared to lymph nodes), and size (mean: 11.4 mm, range: 5-26 mm).13 The differential for the imaging appearance of a parathyroid adenoma includes lymph node, parathyroid hyperplasia, and exophytic thyroid nodule. Variations in CT imaging technique include the 4-dimensional CT (multiphase study assessing for changes in perfusion of contrast) which exploits the early enhancement of parathyroid adenomas with a reported sensitivity and PPV of 89.4% and 93.5%,11 respectively.
In conclusion, ectopic parathyroid adenomas are not an uncommon cause of PH. With only a few cases of ectopic parathyroid adenomas in the piriform sinus previously documented, we present a case that was overlooked on initial imaging studies due to the rare location. These lesions can be challenging to localize; however, an understanding of embryology, close scrutiny of possible ectopic locations, and the application of complementary imaging techniques may prove useful for surgeons and clinicians.
Acknowledgments
The authors would like to thank Dr M. Pelletier-Galarneau from the Department of Nuclear Medicine and Dr K. T. Mai from the Department of Pathology at The Ottawa Hospital/University of Ottawa, Ottawa, Canada, for their contributions.
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.
References
1. Ruda, JM, Hollenbeak, C, Stack, BC. A systematic review of the diagnosis and treatment of primary hyperparathyroidism from 1995 to 2003. Otolaryngol Head Neck Surg. 2005;132(3):359–372.
Google Scholar | SAGE Journals
2. Phitayakorn, R, McHenry, CR. Incidence and location of ectopic abnormal parathyroid glands. Am J Surg. 2006;191(3):418–423.
Google Scholar | Crossref
3. Wang, C . The anatomic basis of parathyroid surgery. Ann Surg. 1976;183(3):271–275.
Google Scholar | Crossref
4. Benson, MT, Dalen, K, Mancuso, AA. Congenital anomalies of the branchial appartus: embryology and pathologic anatomy. Radiographics. 1992;12(5):1175–1189.
Google Scholar | Crossref
5. Miller, DL, Craig, WD, Haines, G. Retropharyngeal parathyroid adenoma: precise preoperative localization with CT and arterial infusion of contrast material. AJR Am J Roentgenol. 1997;169(3):695–696.
Google Scholar | Crossref
6. Guevara, N, Agopian, B, Benisvy, D. Ectopic pyriform sinus parathyroid adenoma. Eur Ann Otorhinolaryngol Head Neck Dis. 2013;130(2):95–98.
Google Scholar | Crossref
7. Dedivitis, RA, Guimarães, AV, Pontes, GB. Multiple ectopic parathyroid adenomas. Sao Paulo Med J. 2004;122(1):32–34.
Google Scholar | Crossref
8. Stojadinovic, A, Shriver, CD, Casler, JD. Endoscopic laser excision of ectopic pyriform sinus parathyroid adenoma. Arch Surg. 1998;133(1):101–103.
Google Scholar | Crossref
9. Johnson, NA, Tublin, ME, Ogilvie, JB. Parathyroid imaging: technique and role in the preoperative evaluation of primary hyperparathyroidism. AJR Am J Roentgenol. 2007;188(6):1706–1715.
Google Scholar | Crossref
10. Rickes, S, Sitzy, J, Neye, H. High resolution ultrasound in combination with colour-doppler sonography for preoperative localization of parathyroid adenomas in patients with primary hyperparathyroidism. Ultraschall Med. 2003;24(2):85–89.
Google Scholar | Crossref
11. Cheung, K, Wang, TS, Farrokhyar, F. A meta-analysis of preoperative localization techniques for patients with primary hyperparathyroidism. Ann Surg Oncol. 2012;19(2):577–583.
Google Scholar | Crossref
12. Gayed, IW, Kim, EE, Broussard, WF. The value of 99mTc-sestamibi SPECT/CT over conventional SPECT in the evaluation of parathyroid adenomas or hyperplasia. J Nucl Med. 2005;46(2):248–252.
Google Scholar
13. Randall, GJ, Zald, PB, Cohen, JI. Contrast-enhanced MDCT characteristics of parathyroid adenomas. AJR Am J Roentgenol. 2009;193(2):W139–W143.
Google Scholar | Crossref
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