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Case Reports
. 2025 Jul 11;3(8):luaf154.
doi: 10.1210/jcemcr/luaf154. eCollection 2025 Aug.

Atypical Parathyroid Tumor Causing Primary Hyperparathyroidism With a Clinical Presentation of a Brown Tumor

Nathanaël Saison  1 , Sandra Fatio  2 , Dominik Pytlik  2 , Stephan Rauthe  3 , Roger Schmid  1 , Chantal Stutz  1
Affiliations
Case Reports

Atypical Parathyroid Tumor Causing Primary Hyperparathyroidism With a Clinical Presentation of a Brown Tumor

Nathanaël Saison et al. JCEM Case Rep. .

Abstract

Brown tumors are rare osteolytic bone lesions linked to primary hyperparathyroidism (pHPT), caused by excessive parathyroid hormone (PTH) production. They feature microfractures, hemorrhage, and hemosiderin deposition. Atypical parathyroid tumors (APT) are uncommon parathyroid neoplasms with histologic features resembling carcinoma but without definitive parathyroid carcinoma (PC) criteria. APTs can rarely lead to brown tumors. We report a 53-year-old male with a history of nephrectomy for renal cell carcinoma and Hodgkin disease. Imaging revealed a growing osteolytic lesion in the left iliac bone. Laboratory findings indicated pHPT with elevated PTH levels. Sonography and 18F-fluorocholine positron emission tomography-computed tomography (PET-CT) identified a right inferior parathyroid tumor. The patient underwent focused parathyroidectomy, and histology confirmed APT with fibrous tracts and trabecular growth features. APT accounts for 0.5% to 4.4% of parathyroid surgeries and may rarely lead to brown tumors. Differentiating brown tumors from malignancies requires biochemical, imaging, and histopathological evaluation. Although APTs generally follow a benign course, long-term surveillance is essential, particularly in familial cases. Further research is needed to investigate the malignancy potential and recurrence risk of rare atypical parathyroid neoplasms. This case highlights the importance of a multidisciplinary approach in their diagnosis and management.

Keywords: atypical parathyroid tumor; brown tumor; parathyroid.

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Figures

Figure 1.
Figure 1.
CT scan imaging demonstrates a 5 × 2 mm osteolytic lesion in the left iliac bone with cortical destruction (white arrow).
Figure 2.
Figure 2.
Histological examination of the bone biopsy reveals fibroblastic tissue with scattered multinucleated osteoclastic giant cells (indicated by arrows), consistent with features of a brown tumor (hematoxylin and eosin; 100×).
Figure 3.
Figure 3.
An ¹8F-fluorocholine PET/CT scan revealed a choline-avid lesion located dorsally to the right of the thyroid, consistent with a parathyroid tumor (white arrow).
Figure 4.
Figure 4.
Histological features of atypical parathyroid tumor with trabecular, nested, and solid areas, and irregular fibrous bands (hematoxylin and eosin; 40×).
See this image and copyright information in PMC

References

    1. Castellano E, Attanasio R, Boriano A, et al. Radiologic manifestation of bone involvement in primary hyperparathyroidism: prevalence and clinical significance in a southern European series. Endocr Pract. 2020;26(9):983‐989. - PubMed
    1. Kalathas T, Kalatha T, Boultoukas E. Brown tumors; a possible pitfall in diagnosing metastatic disease. Hell J Nucl Med. 2010;13(1):15‐17. - PubMed
    1. Marini F, Marcucci G, Giusti F, et al. Parathyroid carcinoma and atypical parathyroid tumor: analysis of an Italian database. Eur J Endocrinol. 2024;191(4):416‐425. - PubMed
    1. Erickson LA, Mete O, Juhlin CC, Perren A, Gill AJ. Overview of the 2022 WHO classification of parathyroid tumors. Endocr Pathol. 2022;33(1):64‐89. - PubMed
    1. Cetani F, Marcocci C, Torregrossa L, Pardi E. Atypical parathyroid adenomas: challenging lesions in the differential diagnosis of endocrine tumors. Endocr Relat Cancer. 2019;26(7):R441‐R464. - PubMed

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