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Year : 2021  |  Volume : 36  |  Issue : 4  |  Page : 457-458  

Air! Places we not ought to see it: Incidentally detected spontaneous pneumomediastinum complicated by cervical emphysema on positron emission tomography/computed tomography


Department of Nuclear Medicine, All India Institute of Medical Sciences, New Delhi, India

Date of Submission06-Apr-2021
Date of Acceptance29-May-2021
Date of Web Publication15-Dec-2021

Correspondence Address:
Dr. Rakesh Kumar
Department of Nuclear Medicine, All India Institute of Medical Sciences, Ansari Nagar, New Delhi - 110 029
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijnm.ijnm_44_21

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   Abstract 


Spontaneous pneumomediastinum is a rare condition, characterized by the presence of air in the mediastinum without any apparent precipitating cause. It is mainly a radiological diagnosis. The onus of differentiating between secondary and spontaneous pneumomediastinum lies on a thorough workup. In addition to etiology, complications such as tension pneumomediastinum, cervical emphysema, and pneumorachis. When present, must be diagnosed promptly. Spontaneous pneumomediastinum is a benign condition which is usually managed conservatively. Although not routinely seen on positron emission tomography/computed tomography, when present, they must be picked up and reported accurately to guide appropriate management of the patient.

Keywords: Cervical emphysema, incidental, paraneoplastic encephalitis, positron emission tomography/computed tomography, spontaneous pneumomediastinum


How to cite this article:
Kumar S, Sharma A, Wakankar R, Majeed AK, Shankar K, Kumar R. Air! Places we not ought to see it: Incidentally detected spontaneous pneumomediastinum complicated by cervical emphysema on positron emission tomography/computed tomography. Indian J Nucl Med 2021;36:457-8

How to cite this URL:
Kumar S, Sharma A, Wakankar R, Majeed AK, Shankar K, Kumar R. Air! Places we not ought to see it: Incidentally detected spontaneous pneumomediastinum complicated by cervical emphysema on positron emission tomography/computed tomography. Indian J Nucl Med [serial online] 2021 [cited 2022 Jan 17];36:457-8. Available from: https://www.ijnm.in/text.asp?2021/36/4/457/332616



Spontaneous pneumomediastinum (SPM) is a rare condition characterized by the presence of free air in the mediastinum without any known precipitating cause(s).[1] Owing to the rarity of the disease, the available literature consists mainly of case series and some retrospective studies with one of them describing an estimated incidence of <1 in 44,000.[2] The pathophysiologic mechanism underlying the development of SPM involves activities that increase intra-alveolar pressure, such as intense coughing, crying, vomiting, and constipation. Physiologic pressure differences exist between the pleura, alveoli, and the mediastinum which aid in respiration. The existing pressure gradient leads to air from alveolar rupture to dissect along the bronchovascular structures to finally accumulate in the mediastinal space.[3] The condition was initially described by Laennec and further characterized by Hamman[1] who initially went on to describe the clinical features in a case series. SPM presents with vague symptoms, the most common being chest discomfort. Due to the wide range of cardiac and respiratory pathologies that present with similar symptoms, SPM is usually overlooked as a differential. The classic clinical triad is described by Hammam consists of pleuritic chest pain, dyspnea, and subcutaneous emphysema.[4] It is known to cause dyspnea in 49%, cough in 36%, neck pain in 36%, and dysphagia in 18% of the affected population.[5] SPM is typically a benign condition. The onus of differentiating between primary and secondary causes of pneumomediastinum such as trauma, gas-producing infection, and esophageal rupture which are all potentially fatal lies on radiological investigations like computed tomography (CT) scan.[6] Complications in SPM although rare; involves conversion into tension or malignant PM,[7] extension into surrounding structures such as pericardial space, retropharyngeal space, retroperitoneal space, and subcutaneous aspect of the neck, spinal canal.[8]

We describe the case of an incidentally detected pneumomediastinum complicated by cervical emphysema in a patient who presented to our department for a whole body 18F-FDG (fluoro-deoxy glucose) positron emission tomography/CT (PET/CT) scan as part of his work up for ruling out paraneoplastic encephalitis [Figure 1]. Due to the rarity of the disease, pneumomediastinum is not routinely encountered on PET/CT. SPM if found during PET/CT studies must be appropriately identified and reported to guide further management of the patient.
Figure 1: A 15-year-old boy presented with low-grade fever without chills, generalized tonic-clonic seizures, and gradual worsening of memory. The initial workup of the patient was inconclusive. The patient was then referred to the Department of Nuclear Medicine at our institute for a whole-body F-18 fluoro-deoxy-glucose positron emission tomography/computed tomography scan with a provisional diagnosis of paraneoplastic encephalitis. No evidence of any metabolically active lesion was noted anywhere in the body. However, air was incidentally detected in the mediastinum and neck spaces, suggestive of a spontaneous pneumomediastinum and cervical emphysema. (a-f) demonstrates axial sections of computed tomography and fused positron emission tomography/computed tomography at various levels as described in the sagittal section (g). (a and b) shows the presence of air outlining the thyroid cartilage and in the retropharyngeal location. (c and d) demonstrates the presence of air around the great vessels of heart. (e and f) Demonstrates the presence of air in the anterior mediastinum

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Informed consent

Informed consent from the patient was obtained to be included in the study.

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 understands that name and initials will not be published and due efforts will be made to conceal the identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
   References Top

1.
Sahni S, Verma S, Grullon J, Esquire A, Patel P, Talwar A. Spontaneous pneumomediastinum: Time for consensus. N Am J Med Sci 2013;5:460-4.  Back to cited text no. 1
    
2.
Macia I, Moya J, Ramos R, Morera R, Escobar I, Saumench J, et al. Spontaneous pneumomediastinum: 41 cases. Eur J Cardiothorac Surg 2007;31:1110-4.  Back to cited text no. 2
    
3.
Macklin MT, Macklin CC. Malignant interstitial emphysema of the lungs and mediastinum as an important occult complication in many respiratory diseases and other conditions: An interpretation of the clinical literature in the light of laboratory experiment. Medicine 1944;23:281-358.  Back to cited text no. 3
    
4.
Asma M, Nesrine F, Ahmed BS, Sameh J, Saoussen CM, Naceur R. Spontaneous pneumomediastinum: Experience in 13 patients. Respir Med Case Rep 2019;28:100946.  Back to cited text no. 4
    
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Abolnik I, Lossos IS, Breuer R. Spontaneous pneumomediastinum. A report of 25 cases. Chest 1991;100:93-5.  Back to cited text no. 5
    
6.
Jougon JB, Ballester M, Delcambre F, Mac Bride T, Dromer CE, Velly JF. Assessment of spontaneous pneumomediastinum: Experience with 12 patients. Ann Thorac Surg 2003;75:1711-4.  Back to cited text no. 6
    
7.
Kirsh MM, Orvald TO. Mediastinal and subcutaneous emphysema complicating acute bronchial asthma. Chest 1970;57:580-1.  Back to cited text no. 7
    
8.
Vrakopoulou GZ, Michalopoulou V, Kormentza CE, Matiatou M, Zografos KG, Toutouzas KG. Pneumomediastinum and pneumopericardium 11 days after Whipple procedure. A case report and review if the literature. Int J Surg Case Rep 2020;71:27-9.  Back to cited text no. 8
    


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