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CASE REPORT
Year : 2012  |  Volume : 11  |  Issue : 1  |  Page : 39-41

Mediastinal Parathyroid Adenoma and Brown Tumors


Department of Nuclear Medicine, Hospital Universitario, Fundación Santa Fé de Bogotá, Bogotá, Colombia

Date of Web Publication19-Jul-2012

Correspondence Address:
P Bernal
Departments of Nuclear Medicine and Diagnostic Imaging, Fundación Santa Fe, Calle 116 # 7 - 75 Piso 2, Bogotŕ
Colombia
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DOI: 10.4103/1450-1147.98748

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   Abstract 

In this report, we describe a rare case of brown tumor and mediastinal parathyroid adenoma. This report emphasizes the value of radionuclide scintigraphy in the setting of persistent disease following parathyroid surgery.

Keywords: Brown tumor, parathyroid adenoma, Tc-99m MIBI


How to cite this article:
Bernal P, Ucros G, Mejia A. Mediastinal Parathyroid Adenoma and Brown Tumors. World J Nucl Med 2012;11:39-41

How to cite this URL:
Bernal P, Ucros G, Mejia A. Mediastinal Parathyroid Adenoma and Brown Tumors. World J Nucl Med [serial online] 2012 [cited 2019 Dec 15];11:39-41. Available from: http://www.wjnm.org/text.asp?2012/11/1/39/98748


   Introduction Top


Parathyroid adenomas are the cause of hyperparathyroidism in about 85% of patients suffering from this disease; and specifically these may arise as a complication of secondary hyperparathyroidism in patients with chronic renal failure, with the loss of feedback auto-regulation mechanism on any of the hyperplasic glands (tertiary hyperparathyroidism). [1] Chronic bone resorption induced by excessive parathormone (PTH) may produce cystic bone lesions throughout the skeleton, called osteitis fibrosa cystica that may present as pathological fractures or as brown tumors with a reported prevalence of 0.1%. [2],[3]

Parathyroid scintigraphy with 99mTc-Sestamibi is an important tool to identify the location of the culprit gland increasing the surgical success and decreasing the time of the procedure. [4] It is particularly useful in post-operative patients with persistent or recurrent hyperparathyroidism, in whom re-exploration may be technically difficult and where the possibility of existence of ectopic parathyroid tissue may be very high.


   Case Report Top


A 59-year-old female with chronic kidney disease and undergoing hemodialysis for nine years, presented with persistently raised parathormone levels and bone pain even after she was submitted to a total parathyroidectomy about a year ago for severe secondary hyperparathyroidism with renal osteodystrophy and intractable bone pain. She was referred for a parathyroid scintigraphy with 99mTc-Sestamibi with the intention to identify a supernumerary and/or ectopic gland.

The scan was performed following administration of 740 MBq (20 mCi) of 99mTc-Sestamibi. Planar images of the neck and mediastinum were acquired at 5, 30, 60 and 120 min, and SPECT/CT images were performed at 120 min with a Siemens Symbia SPECT Camera.

A focus of intense MIBI uptake was detected in the anterior mediastinum on all planar images obtained at 5.10,60 and 120 min [Figure 1]. The SPECT/CT scan confirmed the presence of a Tc-99m MIBI avid soft tissue nodule adjacent to the ascending aorta (size 23 × 17 mm) [Figure 2]a. Histopathological examination confirmed this to be parathyroid adenoma. The SPECT/CT images also revealed multiple expansive septate cystic lesions in the ribs showing minimal MIBI uptake [Figure 2] b-d consistent with "brown tumors".
Figure 1: Tc-99m MIBI scans of neck and thoracic region obtained at 5, 10, 60 and 120 min showing a solitary focus of increased MIBI uptake (arrow) in the ectopic parathyroid located in the anterior mediastinum

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Figure 2: Tc-99m MIBI SPECT-CT study of the chest. Cross sectional images revealed a Tc-99m MIBI avid soft tissue lesion in the anterior mediastinum adjacent to ascending aorta (image (a) red arrow), which was confirmed to be a parathyroid adenoma on histopathological examination. Multiple well-defined marginated expansile lytic lesions (Brown tumors) are noted in the ribs (images (b-d); arrows)

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   Discussion Top


In this report, we describe a rare case of brown tumor and mediastinal parathyroid adenoma. The report emphasizes the value of radionuclide scintigraphy in the setting of persistent disease after parathyroid surgery. In secondary hyperparathyroidism, immediate failure after surgery is not unusual, occurring in about 10-30% of patients. Hence imaging is mandatory prior to re-exploration in order to identify an ectopic or supernumerary gland (about 10% may have a fifth gland) that was missed at initial intervention. [1] The locations of the inferior glands are more variable, they can be found anywhere from above the carotid bifurcation to the mediastinum, [1] with approximately 9% in the last location. [5] Reviewing early and late images together with SPECT maximizes parathyroid lesion detection (sensibility 90%, specificity 98%, accuracy 94%). [6] Hybrid SPECT/CT images provide both morphologic and functional information about an abnormality. The anatomical details of CT provide added value for the precise location of the anomalies, [1],[7] as in this particular case.

Brown tumors are tumor-like lesions without autonomous growth and occur only in the more advanced stages of hyper-parathyroid bone disease; [8] particularly in patients with chronic renal failure. With increasing longevity of hemodialysis patients, such instances of hyper-parathyroidism appear to occur more and more commonly in clinical practice. [9] Brown tumors have become rare due to routine availability of facilities for routine measurement of serum Ca and PTH, allowing early diagnosis and treatment of hyperparathyroidism. [8] Microscopically they are characterized by intensely vascular fibroblastic stroma serving as a background for numerous osteoclast-like multinucleated giant cells and the cysts develop as a result of intraosseous bleeding and tissue degeneration. [3],[10] The presence of hemorrhage, hemosiderin and hypervascularity leads to the brownish color, and thus the name. [3] Radiographically they appear as well-defined marginated expansile lytic lesions that may cause cortical expansion and can occur in monoostotic and polyostotic forms, commonly affecting the mandible, clavicle, ribs, pelvis, and femur. [3]

The 99mTc-sestamibi scan is less sensitive than bone scintigraphy for brown tumor detection, since it shows only large tumors. [8] The precise mechanisms for the increased uptake of 99mTc-sestamibi in a brown tumor is unknown, but seems to be related to increased cellular mitochondrias, increased blood flow, increased capillary permeability, and altered potassium diffusion potentials across mitochondrial and plasma membranes. [8]

After appropriate medical or surgical treatment of the hyperparathyroidism, brown tumor may regress. [3]

 
   References Top

1.Palestro CJ, Tomas MB, Tronco GG. Radionuclide imaging of the parathyroid glands. Semin Nucl Med 2005;35:266-76.  Back to cited text no. 1
[PUBMED]    
2.Fitzgerald P. Endocrinology. In: McPhee SJ, Papadakis MA, Rabow MW, editors. Current medical diagnosis and treatment. 50 th ed. Stanford, CT: Appleton and Lange; 2011.p. 1090-8.  Back to cited text no. 2
    
3.Soundarya N, Sharada P, Prakash N, Pradeep G. Bilateral maxillary brown tumors in a patient with primary hyperparathyroidism: Report of a rare entity and review of literature. J Oral Maxillofac Pathol 2011;15:56-9.  Back to cited text no. 3
[PUBMED]  Medknow Journal  
4.The Society of Nuclear Medicine Procedure Guideline For Parathyroid Scintigraphy. Version 3.0, 2004.  Back to cited text no. 4
    
5.Butterworth PC, Nicholson ML. Surgical anatomy of the parathyroid glands in secondary hyperparathyroidism. J R Coll Surg Edinb 1998;43:271-3.  Back to cited text no. 5
[PUBMED]    
6.Nichols KJ, Tomas MB, Tronco GG, Rini JN, Kunjummen BD, Heller KS, et al. Preoperative parathyroid scintigraphic lesion localization: Accuracy of various types of readings. Radiology 2008;248:221-32.  Back to cited text no. 6
[PUBMED]    
7.Hindié E, Ugur O, Fuster D, O'Doherty M, Grassetto G, Ureña P, et al. 2009 EANM parathyroid guidelines. Eur J Nucl Med Mol Imaging 2009;36:1201-16.  Back to cited text no. 7
    
8.Meng Z, Zhu M, He Q, Tian W, Zhang Y, Jia Q, et al. Clinical implications of brown tumor uptake in whole-body 99mTc-sestamibi scans for primary hyperparathyroidism. Nucl Med Commun 2011;32:708-15.  Back to cited text no. 8
    
9.Fatma LB, Barbouch S, Fethi BH, Imen BA, Karima K, Imed H, et al. Brown tumors in patients with chronic renal failure and secondary hyperparathyroidism: Report of 12 cases. Saudi J Kidney Dis Transpl 2010;21:772-7.  Back to cited text no. 9
[PUBMED]  Medknow Journal  
10.Khalil PN, Heining SM, Huss R, Ihrler S, Siebeck M, Hallfeldt K, et al. Natural history and surgical treatment of brown tumor lesions at various sites in refractory primary hyperparathyroidism. Eur J Med Res 2007;12:222-30.  Back to cited text no. 10
    


    Figures

  [Figure 1], [Figure 2]


This article has been cited by
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[Pubmed] | [DOI]



 

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