An Unusual Retropharyngeal Lesion | Endocrinology | JN Learning | AMA Ed Hub [Skip to Content]
[Skip to Content Landing]

An Unusual Retropharyngeal Lesion

Educational Objective
Based on this clinical scenario and the accompanying image, understand how to arrive at a correct diagnosis.
1 Credit CME

A female smoker in her 50s was referred for hyperparathyroidism and a multinodular goiter. The patient reported symptoms of joint and musculoskeletal pain and fatigue but denied fever, sore throat, abdominal pain, and kidney stones. Her medical history was remarkable for congestive heart failure and schizophrenia. Neck examination revealed no meaningful findings except right thyroid enlargement. Results of laboratory evaluation demonstrated normal white blood cell count, borderline hypercalcemia (10.6 mg/dL), and elevated parathyroid hormone level (208 pg/mL). She underwent ultrasonography at an outside facility, and results demonstrated a 2.2-cm dominant right thyroid nodule with additional smaller thyroid nodules. Findings of preoperative technetium-99m (Tc-99m) sestamibi planar and single-photon emission computed tomographic/computed tomographic (SPECT/CT) imaging (Figure, A) were nonlocalizing for a parathyroid adenoma and showed increased uptake in the dominant right thyroid nodule (Figure, B). Results of an ultrasound-guided biopsy of the thyroid nodule demonstrated a benign colloid nodule with cystic changes. Computed tomography with intravenous contrast was obtained, and findings were initially reported as negative except for right multinodular goiter. However, on additional review, a well-circumscribed fat density mass measuring 3.0 × 2.3 × 1.1-cm was identified in the right retropharyngeal space posterior to the hypopharynx (Figure, C).

Please finish quiz first before checking answer.

You answered correctly!

Read the answer below and download your certificate.

You answered incorrectly.

Read the discussion below and retake the quiz.

A. Ectopic parathyroid lipoadenoma

The patient underwent transcervical excision of the mass, located in the retropharyngeal space posterolateral to the right inferior constrictor muscle at the level of the hypopharynx. There was intraoperative normalization of parathyroid hormone levels, and final pathological results confirmed parathyroid lipoadenoma. Thus, to our knowledge, the present case is the first reported ectopic parathyroid lipoadenoma within the retropharyngeal space. In addition, this case demonstrates how parathyroid lipoadenomas are less reliably detected by Tc-99m SPECT/CT than their typical parathyroid adenoma counterparts, which highlights the value of contrasted CT.

Parathyroid lipoadenoma is a rare variant of parathyroid adenoma with a similar presentation owing to hyperfunctioning parathyroid tissue. The presence of increased fatty stroma differentiates parathyroid lipoadenoma from parathyroid adenoma and also renders it more difficult to identify on preoperative imaging. Although it is uncertain where the fatty stroma originates from, it has been postulated that the same factors that drive growth of parathyroid chief cells are also responsible for fatty growth. Obesity and advanced age may increase this percentage of fatty tissue. Only 70 cases of parathyroid lipoadenoma have been described to date,15 accounting for less than 1% of all cases of hyperparathyroidism, and most ectopic locations have been in the mediastinum.6 Of note, although a liposarcoma may have similar imaging findings to a lipoadenoma, corresponding primary hyperparathyroidism would be unlikely. The imaging characteristics are clearly not consistent with thyroid tissue. An isolated retropharyngeal abscess would be less likely without infectious symptoms as well.

Survey Complete!

Sign in to take quiz and track your certificates

Buy This Activity

JN Learning™ is the home for CME and MOC from the JAMA Network. Search by specialty or US state and earn AMA PRA Category 1 CME Credit™ from articles, audio, Clinical Challenges and more. Learn more about CME/MOC

CME Disclosure Statement: Unless noted, all individuals in control of content reported no relevant financial relationships. If applicable, all relevant financial relationships have been mitigated.

Article Information

Corresponding Author: Michael W. Sim, MD, Department of Otolaryngology–Head and Neck Surgery, Indiana University School of Medicine, 1130 W Michigan St, Ste 400, Indianapolis, IN 46202 (mwsim@iu.edu).

Published Online: September 17, 2020. doi:10.1001/jamaoto.2020.2703

Conflict of Interest Disclosures: None reported.

Additional Contributions: We thank the patient’s mother for granting permission to publish this information.

References
1.
Hyrcza  MD , Sargın  P , Mete  O .  Parathyroid lipoadenoma: a clinicopathological diagnosis and possible trap for the unaware pathologist.   Endocr Pathol. 2016;27(1):34-41. doi:10.1007/s12022-015-9404-5 PubMedGoogle ScholarCrossref
2.
Triviño  A , Varela  J , Ayllón  S .  Mediastinal parathyroid lipoadenoma.   Arch Bronconeumol. 2020;56(5):323. doi:10.1016/j.arbres.2019.04.016PubMedGoogle ScholarCrossref
3.
Fujisawa  S , Inagaki  K , Wada  J .  Parathyroid lipoadenoma: a pitfall in preoperative localization.   Intern Med. 2019;58(8):1183-1184. doi:10.2169/internalmedicine.1249-18 PubMedGoogle ScholarCrossref
4.
Özden  S , Güreşci  S , Saylam  B , Dağlar  G .  A rare cause of primary hyperparathyroidism: parathyroid lipoadenoma.   Auris Nasus Larynx. 2018;45(6):1245-1248. doi:10.1016/j.anl.2018.05.001 PubMedGoogle ScholarCrossref
5.
Aggarwal  A , Wadhwa  R , Aggarwal  V .  Parathyroid lipoadenoma: a rare entity.   Indian J Endocrinol Metab. 2018;22(1):174-176. doi:10.4103/ijem.IJEM_273_17 PubMedGoogle ScholarCrossref
6.
Gowda  K , Matippa  P.   Parathyroid lipoadenoma: a diagnostic pitfall during frozen section evaluation of parathyroid lesions.   Int Clin Pathol J. 2016; 3(2):193-194. doi:10.15406/icpjl.2016.03.00070 Google ScholarCrossref
7.
Nguyen  BD .  Parathyroid imaging with Tc-99m sestamibi planar and SPECT scintigraphy.   Radiographics. 1999;19(3):601-614. doi:10.1148/radiographics.19.3.g99ma10601 PubMedGoogle ScholarCrossref
8.
Alenezi  S , Asa’ad  S , Elgazzar  A.   Scintigraphic parathyroid imaging: concepts and new developments.   Res Rep Nucl Med. 2015;2015(5):9-18.Google Scholar
Want full access to the AMA Ed Hub?
After you sign up for AMA Membership, make sure you sign in or create a Physician account with the AMA in order to access all learning activities on the AMA Ed Hub
Buy this activity
Close
Want full access to the AMA Ed Hub?
After you sign up for AMA Membership, make sure you sign in or create a Physician account with the AMA in order to access all learning activities on the AMA Ed Hub
Buy this activity
Close
With a personal account, you can:
  • Access free activities and track your credits
  • Personalize content alerts
  • Customize your interests
  • Fully personalize your learning experience
Education Center Collection Sign In Modal Right
Close

Name Your Search

Save Search
Close
With a personal account, you can:
  • Access free activities and track your credits
  • Personalize content alerts
  • Customize your interests
  • Fully personalize your learning experience
Close

Lookup An Activity

or

Close

My Saved Searches

You currently have no searches saved.

Close

My Saved Courses

You currently have no courses saved.

Close
With a personal account, you can:
  • Access free activities and track your credits
  • Personalize content alerts
  • Customize your interests
  • Fully personalize your learning experience
Education Center Collection Sign In Modal Right
Close