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Ectopic parathyroid adenoma in the soft palate: a case report Chang, Brent A; Sharma, Anil; Anderson, Donald W Oct 18, 2016

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CASE REPORT Open AccessEctopic parathyroid adenoma in the softpalate: a case reportBrent A. Chang1*, Anil Sharma2 and Donald W. Anderson1AbstractBackground: Ectopic parathyroid adenomas can occur in numerous anatomic locations. While ectopic parathyroidadenomas can rarely occur in the pharyngeal region, this has not previously been described in the soft palate.Case presentation: We report the first case of ectopic parathyroid adenoma within the soft palate. A 59 year oldwoman presented with hyperparathyroidism. She remained persistently hyperparathyroid after initialparathyroidectomy. Repeat exploration for a lesion suspicious on PET-CT for an ectopic parathyroid adenoma in theparapharyngeal region was unsuccessful in treating the hyperparathyroidism. An ectopic adenoma in the softpalate was eventually discovered. Removal through a transoral approach was successful in treating thehyperparathyroidism.Conclusions: Ectopic parathyroid adenomas can occur in various anatomical locations that may be missed evenwith the use of the various imaging modalities. The soft palate should be added to the list of possible ectopiclocations high in the neck.Keywords: Ectopic, Parathyroid adenoma, Case report, HyperparathyroidismBackgroundThe existence of ectopic parathyroid tissue remains asignificant hurdle in the surgical management of hyper-parathyroidism. Embryological development and migra-tory descent to the lower neck predisposes theparathyroid glands to ectopic locations. Ectopic aden-omas have been reported to account for anywhere from4 to 16 % of patients with hyperparathyroidism and arethought to be the cause of a significant portion of failedprimary surgery for hyperparathyroidism [1–3].Ectopic parathyroid glands have been classically de-scribed as occurring in numerous anatomic locations any-where from the angle of the mandible to the mediastinum[4–6]. Most commonly they occur in the mediastinum, inthe path of the vagus nerve and recurrent laryngeal nerve,and within the thyroid parenchyma [7]. Several reportshave described ectopic parathyroid adenomas in more un-usual locations, such as within the hypoglossal nerve [6],posterior triangle of the neck [8, 9], axilla [10] andpericardium [11]. Lesions can less commonly occur higherin the pharyngeal structures with only two reports de-scribing lesions in either the oropharynx or nasopharynx[1, 12]. We present a case of a diagnostically challengingectopic parathyroid adenoma in the soft palate, which hasnot previously been described.Case presentationA 59 year old woman with a 7 year history of recurrentnephrolithiasis and mild hypertension presented with acomplaint of weakness and fatigue with associated boneand joint pain. Further history revealed that she had hadfive previous episodes of urinary calculi requiring sur-gery or lithotripsy. She was also discovered to have hada first degree atrioventricular block and was currentlyawaiting pacemaker insertion. There was no family his-tory of thyroid/parathyroid disorders or history of previ-ous radiation. Physical examination was unremarkable.Laboratory investigations revealed hypercalcemia(2.89 mmol/L), hypophosphatemia (0.78 mmol/L) andelevations in parathyroid hormone (PTH) (15.2 pmol/L).Bone mineral density studies revealed cortical boneosteoporosis.* Correspondence: brent.a.chang@gmail.com1Division of Otolaryngology–Head & Neck Surgery, University of BritishColumbia, 2775 Laurel St., 4th floor Otolaryngology (ENT), Vancouver, BC V5Z1M9, CanadaFull list of author information is available at the end of the article© 2016 The Author(s). Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, andreproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link tothe Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver(http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.Chang et al. Journal of Otolaryngology - Head and Neck Surgery  (2016) 45:53 DOI 10.1186/s40463-016-0165-zA 99mTc-sestamibi scan did not reveal any abnormality.An exploratory parathyroidectomy was then arrangedand the right and left superior parathyroid glands wereremoved, along with a localized biopsy of the left inferiorparathyroid gland. The right upper gland was 1 cm indiameter and was thought to be an adenoma. No inferiorright parathyroid gland was identifiable. She subse-quently remained hyperparathyroid and underwent re-exploration and removal of the previously biopsied leftinferior gland. Again, a right inferior gland was not iden-tified and a right thyroid lobectomy to locate a possibleintra-thyroid adenoma was performed. The final patho-logical analysis of the removed thyroid lobe did notidentify any parathyroid tissue within the thyroid paren-chyma, but there was normal parathyroid tissue in theparatracheal fat removed at the time. Parathyroid hor-mone levels continued to remain persistently elevated.Although subsequent MRI and CT scans remained nega-tive, PET-CT scanning showed a 3 cm region of uptakein the right parapharyngeal region behind the thyroidcartilage at the level of the arytenoids. Selective venoussampling showed increased PTH levels in this area.A third parathyroid exploration was undertaken forelective resection of the suspicious area shown on PET-CT. Frozen section pathology results suggested thepresence of inflammatory tissue secondary to a suturegranuloma from the previous neck exploration. Intraop-erative PTH levels continued to remain elevated. An ex-haustive search of the neck was then undertaken,including skeletonization of the carotid artery to thelevel of the bifurcation, mobilization of the jugular vein,identification of the course of the vagus nerve throughthe neck, dissection down to the cervical fascia and pre-vertebral fascia and mobilization of the pharynx andesophagus from the prevertebral fascia. At this point, itwas thought that the lesion might be in the upper neck.A secondary incision in the upper neck was considered,but the decision was made to defer further exploration.Post-operatively, the patient continued to have ele-vated serum calcium and PTH and repeat venous sam-pling study was performed, again confirming positiveuptake in the proximal right internal jugular vein. A re-peat CT scan of the head and neck (Fig. 1) was obtained;which revealed a 10 × 5 mm mildly enhancing submuco-sal soft tissue lesion within the soft palate extending intothe tonsillar pillar suggestive of a parathyroid adenoma.The patient underwent a successful transoral surgicalremoval of the lesion. Pathology confirmed the presenceof a parathyroid adenoma. As expected, the patient be-came hypocalcemic postoperatively.DiscussionThe occurrence of ectopic parathyroid adenomas cantypically be explained by their embryological development[7, 12–14]. The parathyroid glands develop from the thirdand fourth pharyngeal pouches. The superior parathyroidglands develop from the fourth pharyngeal pouch, whereas the inferior parathyroid glands arise from the thirdpharyngeal pouch and descend a further distance with thethymus, which migrates into the mediastinum. Ectopicparathyroid glands can thus occur anywhere along theembryologic descent of the parathyroid glands. Specific-ally, the parathyroid glands originate from epithelial cellsat dorsal and ventral wings at the distal extremities of thethird and fourth pharyngeal pouches. During normal de-velopment, the parathyroid glands must separate and sub-sequently travel in a caudal direction [15]. It can bepostulated that if this separation did not occur early on,that a parathyroid gland could end up high in thepharyngeal wall. However, because the inferior parathyroidglands are assisted in their migration by being pulledcaudally by the thymus, such a developmental error mightbe rare. The lack of capsular fixation of the parathyroidglands also makes them susceptible to ectopy and unusualanatomic migrations [5].We are aware of only a few reports describing ec-topic parathyroid adenomas in very superior locations.In a series of 288 patients with persistent hyperpara-thyroidism, Jaskowiak et al. described one patient witha lesion in the wall of the nasopharynx near the nasalseptum and one patient with a lesion high in thevagus nerve at the level of the C1-C2 vertebrae [1].Chan et al. reported on a small series of patients withectopic adenomas in the pharyngeal or surroundingstructures [12]. A cervical approach was used for allFig. 1 This image shows a contrast CT scan of the neck, axial view,demonstrating a suspicious mass in the lateral right soft palateChang et al. Journal of Otolaryngology - Head and Neck Surgery  (2016) 45:53 Page 2 of 4of these lesions, except for one case in which a man-dibular osteotomy was used.There are sparse reports in the literature of utilizing atransoral approach to resect ectopic parathyroid aden-omas. The standard surgical approach for re-explorationfollowing persistent hyperparathyroidism is transcervical[1, 16]. A high oblique neck incision is also used whenan undescended parathyroid adenoma is suspected [1, 16].Transoral surgical approaches have been briefly describedfor non-ectopic parathyroid surgery, but are still in the ex-perimental stages [17, 18]. Transoral robotic surgery ap-proaches have also been described for certain ectopicparathyroid adenomas [19].Reoperation for persistent hyperparathyroidism can bechallenging. This case demonstrates some of the challengesof surgical management of persistent hyperparathyroidism.Normal anatomy and tissue planes are often disrupted andsometimes difficult to recognize. While ectopic parathyroidadenomas are thought to be the most common cause ofpersistent hyperparathyroidism following neck exploration,a number of reasons other than ectopic tumors can beresponsible for persistent hyperparathyroidism, such as dis-ease recurrence, surgical inexperience, missed or residualtissue, parathyromatosis and supernumerary glands. Giventhese challenges, localization studies are recommendedprior to reoperation [1, 2].Previous reports in the literature describe an algorithmfor the management of persistent hyperparathyroidism[19, 20]. Similarly, at our institution, the general ap-proach to persistent hyperparathyroidism after previoussurgery involves a careful review of preoperativeimaging, operative notes, and pathology followed byultrasound and a 99mTc-sestamibi scan. If localization re-mains unsuccessful, cross-sectional imaging is employed(e.g. CT or MRI). Selective venous sampling for parathy-roid hormone levels is done only after previous unsuc-cessful parathyroid exploration. 11C-methionine PETscanning has been very useful in localizing parathyroidadenomas that have failed localization by other tech-niques (data not yet published). Intraoperative parathy-roid hormone monitoring and frozen section are usefulat the time of re-exploration.The case illustrates several points regarding diagnosticimaging for hyperparathyroidism. Most commonly,99mTc-sestamibi scan and ultrasound are used as first-line imaging modalities [21]. CT and MRI are generallyused as a second line imaging choice. In this patient,99mTc-sestamibi scan, CT, MRI, PET-CT, and PTH se-lective venous sampling were all utilized. PET-CT,99mTc-sestamibi scan, MRI and even the initial CT scanfailed to localize this ectopic adenoma. Invasive tech-niques such as selective venous sampling are typicallyreserved for cases where non-invasive imaging has failedto yield an answer; however, this case highlights thepotential utility of such methods. Details regarding thespecific utility and pitfalls of these various imaging mo-dalities are described elsewhere [22].ConclusionsThis case demonstrates some of the challenges of surgicalmanagement of persistent hyperparathyroidism. In diag-nostically challenging cases of persistent hyperparathyroid-ism, unusual ectopic locations of parathyroid adenomasmust be considered. Such consideration is necessary inorder to avoid numerous re-operative explorations and theassociated risks to the patient. Instead of the upper rangeof parathyroid glands being stated as the angle of the man-dible, we suggest that the parathyroid adenomas should beconsidered possible at least as high as the nasopharynx.Given the high ectopic potential of these glands, the upperlimiting position may not yet be known.AbbrevationsCT: Computed Tomography; MRI: Magnetic Resonance Imaging; PET-CT: Positron Emission Tomography–Computed Tomography;PTH: Parathyroid hormoneAcknowledgementWe would like to acknowledge Dr. Gregor McGregor for general guidanceand providing clinical materials. We would also like to acknowledge Dr.Nishant Sharma for help with data collection.FundingNo funding was used for this report.Availability of data and materialsThe data used in construction of this case report was obtained directly fromthe clinical chart. No software or databases were used. Anonymized raw datais available upon request.Authors’ contributionsBAC data collection and manuscript preparation; AS manuscript preparation;DWA manuscript preparation and review. All authors read and approved thefinal manuscript.Competing interestsThe authors declare that they have no competing interests.Consent for publicationConsent to publish this work was obtained from the patient in writing and isavailable upon request.Ethics approval and consent to participateEthics approval for this case was not required according to the guidelinesstated by the University of British Columbia Research Ethics Board.Author details1Division of Otolaryngology–Head & Neck Surgery, University of BritishColumbia, 2775 Laurel St., 4th floor Otolaryngology (ENT), Vancouver, BC V5Z1M9, Canada. 2Division of Otolaryngology–Head & Neck Surgery, Universityof Saskatchewan, Saskatoon, Canada.Received: 18 May 2016 Accepted: 12 October 2016References1. Jaskowiak N, Norton JA, Alexander HR, et al. 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Radiol Clin NorthAm. 2011;49(3):489–509. vi.•  We accept pre-submission inquiries •  Our selector tool helps you to find the most relevant journal•  We provide round the clock customer support •  Convenient online submission•  Thorough peer review•  Inclusion in PubMed and all major indexing services •  Maximum visibility for your researchSubmit your manuscript atwww.biomedcentral.com/submitSubmit your next manuscript to BioMed Central and we will help you at every step:Chang et al. Journal of Otolaryngology - Head and Neck Surgery  (2016) 45:53 Page 4 of 4


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