The pathogenesis of paraesophageal empyema in dogs and constancy of radiographic and computed tomography signs are linked to involvement of the mediastinal serous cavity

Abstract

The mediastinal serous cavity is a normal anatomic space in the caudal mediastinum. Aims of this anatomic and case series study were to describe the signs of pathologic expansion of the mediastinal serous cavity observed during computed tomography (CT), review the underlying anatomy, perform a literature review, and evaluate the medical records of several dogs with mediastinal serous cavity empyema (paraesophageal empyema). The mesothelial lined mediastinal serous cavity is a cranial extension of the omental bursa, separated from the peritoneal cavity by the diaphragm, in the dorsal part of the caudal mediastinum, to the right of the esophagus, between the heart base and diaphragm. In five adult, large-breed dogs with surgically and histologically confirmed paraesophageal empyema, macroscopic plant material was found at surgery in two dogs, adherence to adjacent lung was present in three different dogs, accessory lobectomy was performed in two dogs with subacute-chronic pyogranulomatous pneumonia, and one dog had concurrent pyothorax and mediastinitis, but none had esophageal abnormalities. This study expands our understanding of the pathogenesis and basis for the imaging appearance of paraesophageal empyema in dogs by clarifying the underlying anatomic structures that direct development of this condition. The term empyema accurately describes this condition because the purulent material accumulates within an existing body cavity. The study also provides initial evidence that the development of paraesophageal empyema might be due to local extension of lung disease, such as foreign body migration or pneumonia. Computed tomography was helpful for diagnosis, assessing size, and determining the spread of disease.

The Legend of the Buffalo Chest

“…Fenestrations in the mediastinum have also been noted in dogs, horses, cats, and rabbits. 47 , 48 , 49 , 50 , 51 , 52 , 53 For example, in a study of induced pneumothorax in 22 of 24 dogs in which air was injected into one pleural space, these dogs quickly developed bilateral pneumothorax. 47 …”

Dorsal mediastinal haemorrhage in dogs: 4 cases (2010–2018)

“…In the cases confined to the caudo‐dorsal mediastinum (cases 2 and 4), the haemorrhage could have also arisen from the mediastinal serous cavity (Gendron et al . 2018). It is unclear why concurrent pleural effusion (cases 1 to 3) and pericardial effusion (case 1) were present in some cases.…”

“…2017, Gendron et al . 2018). All of these reported conditions share similar imaging features, which include a cavitated, fluid‐filled lesion in the caudo‐dorsal mediastinum mostly located to the right of the oesophagus and with a contrast enhancing rim of variable thickness (Aulakh et al .…”

“…2017, Gendron et al . 2018). None of these reported lesions extended cranially beyond the level of the tracheal bifurcation and attenuation values of the cavitated, fluid filled centre (where reported) ranged from 8 to 30 HU (Gremillion et al .…”

Eine Frage der Betrachtung – Das Mediastinum in der Röntgendiagnostik

“…B. einer Blutung, Mediastinitis [1,3] oder Ausbildung eines paraösophagealen Abszesses sein (▶ Abb. 7 a, b) [10]. Fokale Verbreiterungen und Dichtezunahmen können aus einer zystischen Veränderung resultieren, die bei Hund und Katze selten beschrieben ist [11,12].…”