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  Table of Contents    
PICTORIAL QUIZ
Year : 2020  |  Volume : 37  |  Issue : 1  |  Page : 66-68  

Mediastinal mass mimic


Department of Pulmonary Medicine, ESI-PGIMSR, New Delhi, India

Date of Submission21-Mar-2019
Date of Acceptance08-Sep-2019
Date of Web Publication31-Dec-2019

Correspondence Address:
Dr. Dipti Gothi
Department of Pulmonary Medicine, ESI-PGIMSR, Basaidarapur, New Delhi - 110 015
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/lungindia.lungindia_124_19

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How to cite this article:
Datta A, Patro M, Gothi D. Mediastinal mass mimic. Lung India 2020;37:66-8

How to cite this URL:
Datta A, Patro M, Gothi D. Mediastinal mass mimic. Lung India [serial online] 2020 [cited 2020 Jul 14];37:66-8. Available from: http://www.lungindia.com/text.asp?2020/37/1/66/274410



A 21-year-old nonsmoker man presented with low-grade fever, cough, and streaky hemoptysis for the past 1 month. His medical history and general examination were unremarkable. Respiratory examination revealed rhonchus in the left interscapular area. Hemogram and blood biochemistry were normal. Enzyme-linked immunosorbent assay for human immunodeficiency virus was negative. The chest radiograph showed a heterogeneous opacity in the left lower zone [Figure 1]. The contrast-enhanced computed tomography (CT) scan images are given in [Figure 2].
Figure 1: Chest radiograph in posteroanterior projection showing heterogeneous opacity in the left lower zone

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Figure 2: Contrast-enhanced computed tomography of chest: (a) transverse section mediastinal window at the level of carina, (b) transverse section mediastinal window at the level of the left and right main bronchus, (c) transverse section lung window showing lingular lobe

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   Questions Top


  1. What are the findings on the CT scan?
  2. What is the radiological diagnosis based on the CT scan findings?



   Answers Top


  1. The CT scan shows a heterogeneous-enhancing posterior mediastinal mass with a tiny calcific focus extending from left hilum to left paravertebral region, encasing the descending aorta, left main pulmonary artery, left inferior pulmonary vein, and the subsegmental bronchus of superior segment of left lower lobe [Figure 2]a and [Figure 2]b. Multiple centrilobular nodules and fibrobronchiectatic changes are seen in lingula [Figure 2]c.
  2. Posterior mediastinal mass is due to granulomatous fibrosing mediastinitis (FM).


The differential diagnoses of a posterior mediastinal mass are metastatic carcinoma, lymphoma, neurogenic tumors, and rarely fibrosing medistinitis. Since our patient was young without any smoking history, malignancy was unlikely. The presence of calcification in the lesion and absence of lymphadenopathy made lymphoma unlikely. The neurogenic tumor, i.e., nerve sheeth tumor, sympathetic ganglia tumors, and paraganglioma were also unlikely. The peripheral nerve sheath tumor manifests radiologically as a well-circumscribed mass with well-defined margins, which displaces adjacent structures without direct invasion. The benign sympathetic ganglionic tumors, i.e., ganglioneuromas, are also well marginated. The malignant sympathetic ganglia tumors which can invade the surrounding structures are seen only in children.[1] Paragangliomas have avid contrast enhancement due to a rich capillary network and delayed washout.[2] Since our case did not have any of the typical characteristics of neurogenic tumors, lymphoma, and carcinoma lung, FM was most likely.

There are two radiological subtypes of FM; granulomatous and nongranulomatous variety. The granulomatous variety shows focal, localized mass of soft-tissue attenuation with dense or stippled calcification. The nongranulomatous variety shows diffuse and infiltrative homogenous soft-tissue masses throughout the mediastinum involving multiple compartments without calcification.[3],[4] Secondary lung parenchymal changes, such as atelectasis, consolidation, nodules, and infiltrations, can also be found with granulomatous variety.[5] Thus, the radiological findings in our patient were consistent with granulomatous FM.

A fiber optic bronchoscopy was performed to prove the diagnosis and determine the etiology. It showed extrinsic compression of superior segment left lower lobe bronchus. Transbronchial lung biopsy revealed epithelioid cell granuloma with caseation necrosis. The special stains for fungus including histoplasma were negative. He was thus diagnosed with granulomatous FM due to tuberculosis and started on antitubercular treatment. The follow-up CT scan after 2 months showed regression of the lesion [Figure 3].
Figure 3: Comparison of computed tomography image before and after treatment: (a) initial computed tomography, same as Figure 2a, (b) follow-up image after 2 months of antitubercular treatment

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   Discussion Top


FM, also known as mediastinal fibrosis or sclerosing mediastinitis, is a rare, benign but progressive condition characterized by proliferation of the fibrous tissue within the mediastinum.[6] It ranges from a benign clinical course to complications, such as obstruction of vascular, airway, and esophageal structures.[3] The granulomatous variety can be due to histoplasmosis, sarcoidosis, tuberculosis, and other fungal infections, such as aspergillosis, blastomycosis, cryptococcosis, and mucormycosis.[6] In our case, although the biopsy specimen demonstrated granuloma, the residency in nonendemic area, absence of fungal element and stain for histoplasmosis, immunocompetent status of the patient, and presence of caseation ruled out histoplasmosis, other fungal etiology, and sarcoidosis. Bronchoscopy may reveal extrinsic compression of the large airways, but bronchoscopic biopsy usually fails to give accurate histological diagnosis. It was a rare case where transbronchial lung biopsy proved the diagnosis.

The literature on granulomatous FM due to tuberculosis is scant.[7],[8] The treatment options range from medical, surgical, to palliative care only. Antitubercular therapy should be given in cases where definite diagnoses have been established. Corticosteroid has limited benefit.[4],[7],[9] Our patient responded to antitubercular therapy without steroids.

To conclude, granulomatous mediastinal fibrosis is a radiological diagnosis. Tuberculous granulomatous FM, one of the rare differential diagnoses, should be kept in mind while dealing with posterior mediastinal masses.

Declaration of patient consent

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

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
   References Top

1.
Pavlus JD, Carter BW, Tolley MD, Keung ES, Khorashadi L, Lichtenberger JP 3rd. Imaging of thoracic neurogenic tumors. AJR Am J Roentgenol 2016;207:552-61.  Back to cited text no. 1
    
2.
Baez JC, Jagannathan JP, Krajewski K, O'Regan K, Zukotynski K, Kulke M, et al. Pheochromocytoma and paraganglioma: Imaging characteristics. Cancer Imaging 2012;12:153-62.  Back to cited text no. 2
    
3.
Jain N, Chauhan U, Puri SK, Agrawal S, Garg L. Fibrosing mediastinitis: When to suspect and how to evaluate? BJR Case Rep 2016;2:20150274.  Back to cited text no. 3
    
4.
Parish JM, Rosenow EC 3rd. Mediastinal granuloma and mediastinal fibrosis. Semin Respir Crit Care Med 2002;23:135-43.  Back to cited text no. 4
    
5.
Lima TC, Marchiori E, Capone D, Barreto MM, Rodrigues RS, Zanetti G. FM: A case report. Radiol Bras 2009;42:337-9.  Back to cited text no. 5
    
6.
McNeeley MF, Chung JH, Bhalla S, Godwin JD. Imaging of granulomatous fibrosing mediastinitis. AJR Am J Roentgenol 2012;199:319-27.  Back to cited text no. 6
    
7.
Wu Z, Jarvis H, Howard LS, Wright C, Kon OM. Post-tuberculous fibrosing mediastinitis: A review of the literature. BMJ Open Respir Res 2017;4:e000174.  Back to cited text no. 7
    
8.
Hu Y, Qiu JX, Liao JP, Zhang H, Jin Z, Wang GF, et al. Clinical manifestations of fibrosing mediastinitis in Chinese Patients. Chin Med J (Engl) 2016;129:2697-702.  Back to cited text no. 8
    
9.
Kuranga AO, Eubank AM, Bowling MR. FM: A review of epidemiology, diagnosis and management. Int J Respir Pulm Med 2018;5:079.  Back to cited text no. 9
    


    Figures

  [Figure 1], [Figure 2], [Figure 3]



 

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