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INTERESTING IMAGE
Year : 2020  |  Volume : 35  |  Issue : 4  |  Page : 364-366  

Metastatic thymic carcinoma on restaging 18F-fluorodeoxyglucose positron emission tomography-computed tomography


1 Department of Nuclear Medicine, Penang Adventist Hospital, George Town, Penang, Malaysia
2 Department of Oncology, Penang Adventist Hospital, George Town, Penang, Malaysia

Date of Submission04-Jun-2020
Date of Decision13-Jun-2020
Date of Acceptance19-Jun-2020
Date of Web Publication21-Oct-2020

Correspondence Address:
Dr. Alex Cheen Hoe Khoo
Department of Nuclear Medicine, Penang Adventist Hospital, 465, Jalan Burma, 10350 George Town, Penang
Malaysia
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijnm.IJNM_123_20

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   Abstract 


Thymic carcinoma is a rare thymic epithelial cancer which is not only locally invasive but also highly aggressive disease. The prognosis for this cancer is poor and the surgery remains the mainstay of treatment. Thymic carcinomas have been shown to metastasize to the lymph nodes, lung, and liver. A 63-year old male who was successfully treated for thymic cancer in 2015, presented with metastatic disease recurrence to the spinal cord. We share interesting images of the spinal cord lesions as well as pituitary metastases that were incidentally detected on restaging 18F-fluorodeoxyglucose positron emission tomography-computed tomography.

Keywords: 18F-fluorodeoxyglucose positron emission tomography-computed tomography, magnetic resonance imaging, metastases, pituitary, spinal cord, thymic carcinoma


How to cite this article:
Hoe Khoo AC, Ang SF. Metastatic thymic carcinoma on restaging 18F-fluorodeoxyglucose positron emission tomography-computed tomography. Indian J Nucl Med 2020;35:364-6

How to cite this URL:
Hoe Khoo AC, Ang SF. Metastatic thymic carcinoma on restaging 18F-fluorodeoxyglucose positron emission tomography-computed tomography. Indian J Nucl Med [serial online] 2020 [cited 2020 Nov 30];35:364-6. Available from: https://www.ijnm.in/text.asp?2020/35/4/364/298736



A 63-year-old male with a squamous cell variant of thymic carcinoma had complete surgical resection of the tumor and adjuvant chemoradiation in 2015. He was apparently well posttreatment until he presented with progressive left hemiparesis in 2019. Decompressive surgery and radiotherapy were performed for metastatic extradural spinal cord recurrence at the level of C6–C7 vertebrae. Nonetheless, his condition continued to deteriorate and 18F-Fluorodeoxyglucose (18F-FDG) positron emission tomography-computed tomography (PET-CT) was performed to restage the disease. [Figure 1]a and [Figure 1]b show the axial fused PET-CT images of incidental findings of 18F-FDG avid lesions at the pituitary fossa and the left lateral aspect of the pons, respectively, whereas [Figure 1]c and [Figure 1]d show the multiple foci of 18F-FDG avid lesions in the spinal cord at the cervical and lumbar regions (white arrows).
Figure 1: (a and b) The axial fused positron emission tomography-computed tomography images of incidental findings of 18F-fluorodeoxyglucose avid lesions at the pituitary fossa and the left lateral aspect of the pons respectively whereas (c and d) the multiple foci of 18F-fluorodeoxyglucose avid lesions in the spinal cord at the cervical and lumbar regions (white arrows)

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Magnetic resonance imaging of the brain and spine was subsequently performed to assess the pituitary and spinal cord lesions. [Figure 2]a and [Figure 2]b show axial T2-weighted fluid-attenuated inversion recovery (FLAIR) sequence images of the pituitary tumor and extradural lesion at the left prepontine cistern. [Figure 2]c and [Figure 2]d show the T2-weighted fast relaxation fast spin-echo sequence sagittal images of the extradural and intradural extramedullary drop metastases, respectively. Thymic carcinoma is a rare thymic epithelial cancer occurring with a peak incidence of 1.06/100,000 population in the United States of America.[1] Thymic carcinomas are highly aggressive, locally invasive, and frequently present in the advanced stages with a 5-year survival of 30%–50%.[2] Neoadjuvant or adjuvant therapy has been shown to improve survival.[2],[3] However, the choice of chemotherapy for advanced disease is unclear and largely based on recommendations with cisplatin-based chemotherapy being the most common regimen.[3],[4] Recurrence or metastasis occurs in approximately one-third of patients with completely resected thymic carcinoma with the median time from initial surgery to metastasis of 3.6 months; compared to 68.8 months in high-risk thymoma [5] Thymic carcinomas frequently metastasize to the regional nodes, lung, liver, adrenal, spleen, bone, and brain.[2] Although rare, spinal cord metastases have been documented in case reports and case series [6] There is limited literature of thymic carcinoma metastases to the pituitary gland.[7] Our patient was fortunate not to suffer from any pituitary-related complications though he had progressive paraparesis of the lower limbs. The pituitary lesion is presumed to be metastatic as it is new. Biopsy of the lesion was suggested but not done due to the patient's financial constraints. 18F-FDG PET-CT is largely used to differentiate low-risk thymoma from high-risk thymoma and thymic cancer, as it is helpful in determining the surgical approach and neoadjuvant treatment.[8],[9] The incidental detection of the pituitary metastasis, in this case, highlights the sensitivity of 18F-FDG PET-CT in detecting metastatic lesions. Furthermore, early detection of treatment failure is important as it is still unclear which chemotherapy regime works best. As metabolic changes precede anatomical changes, responders and nonresponders can be identified earlier with 18F-FDG PET-CT.[10],[11]
Figure 2: (a and b) Axial T2-weighted fluid-attenuated inversion recovery sequence images of the pituitary tumor and extradural lesion at the left prepontine cistern. (c and d) The T2-weighted fast-relaxation fast-spin echo sequence sagittal images of the extradural and intradural extramedullary drop metastases respectively

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Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given his consent for his images and other clinical information to be reported in the journal. The patient understand that name and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.

Acknowledgment

The authors would like to acknowledge the patient who gave his consent for the publication of this article

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
   References Top

1.
Hsu CH, Chan JK, Yin CH, Lee CC, Chern CU, Liao CI. Trends in the incidence of thymoma, thymic carcinoma, and thymic neuroendocrine tumor in the United States. PLoS One 2019;14:e0227197.  Back to cited text no. 1
    
2.
Eng TY, Fuller CD, Jagirdar J, Bains Y, Thomas CR Jr. Thymic carcinoma: State of the art review. Int J Radiat Oncol Biol Phys 2004;59:654-64.  Back to cited text no. 2
    
3.
Yang X, Zhuo M, Shi A, Yang S, Wang Z, Wu M, et al. Optimal first-line treatment for advanced thymic carcinoma. Thorac Cancer 2019;10:2081-7.  Back to cited text no. 3
    
4.
Wei ML, Kang D, Gu L, Qiu M, Zhengyin L, Mu Y. Chemotherapy for thymic carcinoma and advanced thymoma in adults. Cochrane Database Syst Rev. 2013;2013:CD008588.  Back to cited text no. 4
    
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Khandelwal A, Sholl LM, Araki T, Ramaiya NH, Hatabu H, Nishino M. Patterns of metastasis and recurrence in thymic epithelial tumours: longitudinal imaging review in correlation with histological subtypes. Clin Radiol 2016;71:1010-7.  Back to cited text no. 5
    
6.
Jee TK, Lee SH, Kim HJ, Kim ES, Eoh W. Spinal metastasis of thymic carcinoma as a rare manifestation: a summary of 7 consecutive cases. Korean J Spine 2014;11:157-61.  Back to cited text no. 6
    
7.
Kanayama S, Matsuno A, Nagashima T, Ishida Y. Symptomatic pituitary metastasis of malignant thymoma. J Clin Neurosci 2005;12:953-6.  Back to cited text no. 7
    
8.
Sung YM, Lee KS, Kim BT, Choi JY, Shim YM, Yi CA. 18F-FDG PET/CT of thymic epithelial tumors: usefulness for distinguishing and staging tumor subgroups. J Nucl Med 2006;47:1628-34.  Back to cited text no. 8
    
9.
Treglia G, Sadeghi R, Giovanella L, Cafarotti S, Filosso P, Lococo F. Is (18) F-FDG PET useful in predicting the WHO grade of malignancy in thymic epithelial tumors? A meta-analysis. Lung Cancer 2014;86:5-13.  Back to cited text no. 9
    
10.
Thomas A, Mena E, Kurdziel K, Venzon D, Khozin S, Berman AW, et al. 18F-fluorodeoxyglucose positron emission tomography in the management of patients with thymic epithelial tumors. Clin Cancer Res 2013;19:1487-93.  Back to cited text no. 10
    
11.
Segreto S, Fonti R, Ottaviano M, Pellegrino S, Pace L, Damiano V, et al. Evaluation of metabolic response with F-FDG PET-CT in patients with advanced or recurrent thymic epithelial tumors. Cancer Imaging 2017;17:10.  Back to cited text no. 11
    


    Figures

  [Figure 1], [Figure 2]



 

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