Elsevier

Endocrine Practice

Volume 12, Issue 2, March–April 2006, Pages 131-136
Endocrine Practice

Original Article
Parathyroid Lipoadenomas: A Rare Cause of Primary Hyperparathyroidism

https://doi.org/10.4158/EP.12.2.131Get rights and content

ABSTRACT

Objective

To review one institution’s experience with parathyroid lipoadenomas and to report the associated clinical characteristics.

Methods

We present a case series of parathyroid lipoadenomas. A parathyroid lipoadenoma was defined as a single adenoma with more than 50% fat on histologic examination in conjunction with primary hyperparathyroidism and resolution of hypercalcemia postoperatively. Patients who fulfilled the diagnostic criteria were identified from the surgical pathology files of the Mayo Clinic.

Results

Five cases of parathyroid lipoadenomas, including 1 oxyphil lipoadenoma, were identified during the period from 1971 to 2001. The clinical picture of the study subjects resembled that of a typical patient with primary hyperparathyroidism. Parathyroid lipoadenomas were identified in 3 women (60%) and 2 men (40%), and only 1 patient presented with possible hypercalcemia-related symptoms of nephrolithiasis and hip fracture, leading to diagnosis. The mean serum calcium concentration was 11.1 mg/dL. Preoperatively, all study subjects had elevation of serum parathyroid hormone levels. Two of 3 patients (67%) had the tumor identified preoperatively by neck ultrasonography.

Conclusion

A parathyroid lipoadenoma is a rare cause of primary hyperparathyroidism. The clinical features of this pathologic entity are similar to those of the more common pathologic variants of parathyroid disease associated with primary hyperparathyroidism. (Endocr Pract. 2006;12:131-136)

Section snippets

INTRODUCTION

Primary hyperparathyroidism (HPT) is a common disease, estimated to be the third most diagnosed endocrine disorder (1). The clinical presentation usually consists of an elevated serum calcium level in an otherwise asymptomatic patient (2). The normal parathyroid gland contains chief cells and a few oxyphil cells arranged in a branching, cordlike configuration, surrounded by stromal tissue. Chief cells are the main source of parathyroid hormone (PTH), and chief cell parathyroid adenomas are the

MATERIAL AND METHODS

After approval from the Mayo Foundation Institutional Review Board, we searched the diagnostic medical record index, surgical index, and pathology database for parathyroid lipoadenomas. During the period when our cases were identified (1971 to 2001), our institution registered 9,530 cases of HPT and performed 7,120 parathyroidectomies. These numbers did not include patients with clinically unrecognized persistent hypercalcemia, who constitute 16% of patients with HPT in the community (29).

Clinical Profile

Three women (60%) and 2 men (40%) were identified, with a mean age of 62 years (range, 51.5 to 83) at diagnosis. Only 1 patient presented with possible hypercalcemia-related symptoms (history of left hip fracture and kidney stones). Another patient had asymptomatic kidney stones and osteopenia noted on radiography, and a third patient had only evidence of osteopenia on radiography. Bone densitometry was not performed in any patient. The mean duration (± SD) of clinically recognized hypercalcemia

DISCUSSION

Primary HPT due to a parathyroid lipoadenoma was associated with modest hypercalcemia and few clinical symptoms in our cohort. Only 1 study subject presented with possible hypercalcemia-related symptoms in the form of renal stones and a hip fracture. Thus, the clinical presentation is similar to that seen in patients with primary HPT due to the typical chief cell parathyroid adenoma. Although the small number of study subjects may bias any conclusion about the clinical presentation, this cohort

CONCLUSION

Overall, parathyroid lipoadenomas are a rare cause of primary HPT. Their clinical features are characterized by modest hypercalcemia without symptoms, similar to typical primary HPT due to chief cell parathyroid adenomas. The difficulty of preoperative localization of parathyroid lipoadenomas with use of nuclear scans may be due to the high stromal fat content, and the additional use of ultra-sonography may be beneficial. Further studies evaluating the trends of parathyroid pathologic features

ACKNOWLEDGMENT

We thank Michelle Papaconstandinou for assistance with manuscript preparation.

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