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Descending necrotising mediastinitis: a report of misdiagnosis as thoracic aortic dissection
  1. S-L Chou1,
  2. C-H Chern1,
  3. J-D Chen2,
  4. C-K How1,
  5. L-M Wang1,
  6. C-H Lee1
  1. 1Department of Emergency Medicine, Veterans General Hospital-Taipei, National Yang-Ming University, Taiwan, ROC
  2. 2Department of Radiology, Veterans General Hospital-Taipei
  1. Correspondence to:
 Dr C-H Chern
 Department of Emergency Medicine, Veterans General Hospital-Taipei, Taiwan, ROC (112); chchern2002yahoo.com.tw

Abstract

Descending necrotising mediastinitis is an uncommon disease in the emergency department. Early recognition is important for a good prognosis for this fatal condition. This report describes a case of a healthy 79 year old woman who was seen in the urgent care centre with the initial presentation of chest pain. Misdiagnosis was made because of the mis-reading of a flap-like artefact over the ascending aorta and difficulty interpreting subtle change of mediastinal soft tissue infiltration. The patient was then treated as dissecting aneurysm over ascending aorta until her condition deteriorated. Although aggressive treatment comprising thoracotomy, cervical incision and drainage, and antibiotics were begun, the response was poor. Emergency physicians should be familiar with this rare but highly lethal disease. Correlation should be made in a patient complaining about chest pain, especially combined with fever, sore throat, dysphagia, or neck swelling.

  • descending necrotising mediastinitis
  • mediastinitis
  • acute tonsillitis
  • peritonsillar abscess
  • chest pain

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Chest pain is a commonly encountered symptom in the emergency department (ED). Clinicians in the ED usually focus on the cardiovascular causes of chest pain. In this report, we present a case of descending necrotising mediastinitis (DNM) attributble to tonsillar infections, which was misdiagnosed as dissecting aneurysm initially. Reviewing the literature, there has been only one report of DNM from dental infection in the emergency medicine literature.1 Although chest pain is a frequent manifestation of oropharyngeal or deep neck infection with extension to chest,1–7 emergency physicians usually focus on more common causes of chest pain and are unfamiliar with this rare but highly mortal and morbid disease. We present her clinical picture and, through literature review, discuss the clinical pitfalls for this case.

CASE REPORT

The patient was a 79 year old woman, who came to our ED with complaints of chest pain, dysphasia, and general weakness for days. Five days before her transferral to our ED, she was sent to a regional teaching hospital ED because of severe chest pain. With a negative result for electrocardiogram, normal cardiac enzyme activity, and somewhat mild wide mediastinum, her severe chest pain led the physicians to put the aortic dissection into the differential diagnoses list. Initial contrast enhanced computed tomography (CT) of her chest revealed a “flap” over the ascending aorta (while some increased infiltration and minimal fluid accumulations over mediastinal fat surrounding her tracheal, carina, and oesophagus were neglected) (fig 1) and aortic dissection was diagnosed. She was sent to the intensive care unit for continuous monitoring, mainly for the blood pressure and pain control. During her stay in the intensive care unit, her chest pain subsided partially but she became weaker and had a swallowing problem. Under the impression of exacerbation of her dissection, she was transferred to our hospital for further evaluation and treatment. Tracing her history, she had only a resection of skin tumour over her leg with an uneventful consequence. Reviewing the clinical course before and during her stay in that teaching hospital, we found she had a fever and “common cold” before the admission and progressive dysphagia and sore throat during hospitalisation. At our ED, physical examination showed that she was clear with stable vital signs but had mildly acute distress. A throat examination showed mild right tonsillar enlargement with pus discharge and a neck examination showed no pronounced swelling or tenderness. Findings for the rest of the physical examination were unremarkable. Our blood tests showed mild leucocycytosis and a high C reactive protein (290 mg/l). An arterial blood gas analysis showed mild hypoxia (PO2 67 mm Hg). A chest radiograph had severe mediastinal widening, especially over the right superior region. Because of concern about the worsening of clinical conditions, contrast enhanced CT of her neck and chest was repeated and showed soft tissue swelling of her right tonsil with ill defined multi-loculated abscesses over the peritonsillar and retropharyngeal spaces, with downward extension into superior mediastinum (fig 2). Under the diagnosis of mediastinitis with abscesses formation, emergency open thoracotomy was done with insertion of a chest tube to drain the abscess. Pus culture showed a mixture of bacteria (anaerobic Gram positive bacilli, Peptosstreptococcus species, Prevotella species). However, unfortunately, because of her far advanced infectious condition, progressive multiple organ failure attributable to sepsis developed and she died on the 20th day after admission to our hospital.

Figure 1

 Supine chest film showed widening of mediastinum. Contrast enhanced CT scan of chest showed some increased infiltration and minimal fluid accumulations (white arrow) over mediastinal fat surrounding the tracheal (short arrow) and oesophagus (long arrow). A curvilinear artefact (arrow head) is seen over left anterolateral aspect of ascending aorta in one image at lower level, which was initially misdiagnosed as intimal flap in aortic dissection.

Figure 2

 Five days later, the supine chest film showed progressive enlargement of mediastinum. Contrast enhanced CT of chest disclosed noticeable enlargement of mediastinum with multi-loculated abscesses (white arrow) around the trachea (short arrow) and superior vena cava (long arrow), more prominent over the right paratracheal region. The abscesses (white arrow) also extended downward along the descending aorta (small arrow).

DISCUSSION

Reviewing the literature, DNM is an uncommon disease. DNM originates most commonly from deep neck infection attribtuable to odontogenic infection. Other causes include peritonsillar abscess, retropharyngeal abscess, etc.1,3,4,8 In DNM, patients usually present with neck swelling, chest pain, dyspnea, dsyphagia, and/or respiratory distress.1,3,5,6,9,10 Delay in diagnosis is commonly noted, leading to the high mortality rates (40%–60%) in some series.1,8 Traditional radiological examinations might show widening of the mediastinal shadow, widening of the retrovisceral space, increasing thickness of the retropharyngeal, and retrotracheal soft tissue space of neck only in a far advanced condition.4,8,11 Contrast enhanced CT of the chest has been a useful and reliable imaging tool to make the diagnosis.1,5,9,11 Concerning the management, in addition to antibiotics to cover both aerobes and anaerobes, it seems that aggressive operative procedures with standard posterolateral thorocotomy is the most effective treatment.1,4–6,8,9,12–14

In this report, we presented a case of DNM, which originated from tonsillitis and then peritonsillar and retropharyngeal abscess with deep neck and mediastinal extension and misdiagnosed as thoracic aortic dissection because of its main clinical features of chest pain and widening of mediastinum. The possible causes of misdiagnosis stem from unfamiliarity with this rare disease and misreading of the chest CT because of difficulty interpretating mediastinal soft tissue infiltation. Two clinical lessons could be learnt from our case. Firstly, for patients with peritonsillar infection, a commonly encountered disease in ED, inquiry of chest pain and other related clinical presentations might remind clinicians of the possibility of extension of infection into deep neck and mediastinum; and for patients with chest pain, other than the commonly mentioned conditions, a search for the possibility of mediastinal infection is necessary. Chest pain is the common presentation in the extension process of neck infection into the mediastinum, while in the differential diagnoses of chest pain, clinicians usually focus on cardiovascular causes and DNM is rarely mentioned and emphasised. Secondly, familiarity with this disease and clinical correlation in some clinical conditions (especially chest pain, sepsis, respiratory distress, dysphagia, neck swelling associated with oropharyngeal infections) might be the keystone to obtain an earlier diagnosis and a better prognosis. Iyoda et al have reported that the mortality in Japanese cases decreased from 50% (12 of 24) before 1989 to 21.7% (13 of 60) after 1980 because of the improved recognition of DNM.13

REFERENCES

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