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INTERESTING IMAGE
Year : 2017  |  Volume : 32  |  Issue : 1  |  Page : 57-58  

Detection of thymoma on 99mtc mibi scintigraphy: Revisiting the past


Department of Nuclear Medicine and PET/CT, All Institute of Medical Sciences, New Delhi, India

Date of Web Publication17-Jan-2017

Correspondence Address:
Chetan D Patel
Department of Nuclear Medicine and PET, All India Institute of Medical Sciences, New Delhi
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0972-3919.198484

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   Abstract 

Although thymoma is a rare tumor, it is the most common anterior mediastinal tumor, usually affecting the adults in their fifth and sixth decade. We present a case of 68-year-old man with history of myocardial infarction, who presented to the cardiology OPD with recent onset of exertional dyspnea. On 99mTc MIBI myocardial perfusion SPECT, there was an extra cardiac accumulation of radiotracer in the anterior mediastinum just above the heart, which later was diagnosed as thymoma on histopathology.

Keywords: Thymoma, SPECT, 99mTc MIBI


How to cite this article:
Parida GK, Roy SG, Sharma A, Patel CD. Detection of thymoma on 99mtc mibi scintigraphy: Revisiting the past. Indian J Nucl Med 2017;32:57-8

How to cite this URL:
Parida GK, Roy SG, Sharma A, Patel CD. Detection of thymoma on 99mtc mibi scintigraphy: Revisiting the past. Indian J Nucl Med [serial online] 2017 [cited 2019 Dec 16];32:57-8. Available from: http://www.ijnm.in/text.asp?2017/32/1/57/198484

We report a case of a 68-year-old man with history of inferior wall myocardial infarction 12 years back, who presented to the cardiologist with recent onset exertional dyspnea for past couple of months. He was then referred to our nuclear cardiology laboratory for Tc-99m MIBI (Methoxy Isobutyl Isonitrile) myocardial perfusion SPECT (MPS) to look for any inducible ischemia. He underwent treadmill exercise stress on Bruce protocol and was imaged. The study revealed scarred myocardium in the mid and proximal inferior wall, with mild stress induced ischemia in the inferolateral wall. Surprisingly, accumulation of radiotracer was also noted in the mediastinum just above the heart. To further evaluate this abnormal extra cardiac activity, the patient underwent CECT thorax, which showed a soft tissue density anterior mediastinal mass with necrosis and calcification. Based upon CECT features two differential diagnoses were considered: germ cell tumor (GCT) and thymoma. Later, the diagnosis was confirmed to be thymoma on biopsy.

Thymoma is a rare tumor affecting mainly adults in their fifth and sixth decade. Most of the thymomas arise from the anterior mediastinum.[1] Pathologically they can be either benign (type A, AB, B1), high risk (B2 and B3), or malignant (type C).[2] However, Tc-99m MIBI uptake has been reported in both malignant and benign thymomas.[3],[4],[5],[6] And it has been noted that MIBI uptake in thymoma directly correlates with its pathological grading that is more intense is the uptake higher is the grading.[6] The pathophysiology behind MIBI accumulation is increased number of mitochondrias in the hypercelluar matrix of the thymomas.[3] The incidence of these extra cardiac MIBI accumulations like thymoma have been reported in around 1% of patients undergoing MPS.[7] So it is of utmost importance to look for such abnormal tracer distributions during MPS reporting.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
   References Top

1.
Santana L, Givica A, Camacho C. Armed Forces Institute of Pathology. Best cases from the AFIP: thymoma. Radiographics. 2002;22.  Back to cited text no. 1
    
2.
Müller-Hermelink HK, Marx A. Thymoma. Curr Opin Oncol 2000;12:426-33.  Back to cited text no. 2
    
3.
Adalet I, Kocak M, Ece T, Yilmazbayhan D, Cantez S. Tc-99m MIBI and TI-201uptake in a benign thymoma. Clin Nucl Med 1995;20:733-4.  Back to cited text no. 3
    
4.
Aydın F, Sürer Budak E, Dertsiz L, Belgi A, Arslan G, Güngör F. Incidental detection of a benign thymoma on Tc-99m MIBI myocardial perfusion study. Mol Imaging Radionucl Ther 2011;20:73-4.  Back to cited text no. 4
    
5.
Kim SJ, Kim IJ, Kim YK. Tc-99m MIBI, Tc-99m, tetrofosmin, and Tc-99m (V) DMSA accumulation in recurrent malignant thymoma. Clin Nucl Med 2002;27:30-3.  Back to cited text no. 5
    
6.
Fiorelli A, Vicidomini G, Laperuta P, Rambaldi P, Mansi L, Rotondo A, Santini M. The role of Tc-99m-2-methoxy-isobutyl-isonitrile single photon emission computed tomography in visualizing anterior mediastinal tumor and differentiating histologic type of thymoma. Eur J Cardiothorac Surg 2011;40:136-42.  Back to cited text no. 6
    
7.
Gedik GK, Ergün EL, Aslan M, Caner B. Unusual extracardiac findings detected on myocardial perfusion single photon emission computed tomography studies with Tc-99m sestamibi. Clin Nucl Med 2007;32:920-6.  Back to cited text no. 7
    




 

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