Mediastinal abscess

Mediastinal Abscess. Mediastinal abscesses are most often seen after cardiac surgery. Especially if a parasternal access is necessary, the preinterventional planning CT is performed in an arterial and a venous phase in order to visualize the internal mammary artery and vein. To avoid a pneumothorax, drainage placement has to be conducted after dissection of the parasternal soft tissue, using sterile saline. With respect to the large mediastinal vessels, CT guidance and the Seldinger technique are preferred for safe catheter placement. 

Watanakunakom C. Successful novel drainage treatment of mediastinal abscess complicating tracheostomy. Chest 1989 96 946-948. 

Post-operative complications including sternal wound and mediastinal infection are also a problem, occurring in 7% of cardiac transplant recipients (Miller et al. 1993). On chest CT, retrosternal fluid and/or air collections are common within the first 2 weeks of surgery and sampling may be required to determine if these are infected or not (Fig. 2.2.5) Persistent retrosternal fluid and/or air collections on CT after 2 weeks from surgery are indicative of infection (Jolles et al. 1996). Mediastinal abscesses often demonstrate rim enhancement with intravenous contrast. Complications of chronic mediastinal infections include sinus tracts and fistula, as well as pseudoaneurysm formation of the aorta (Knisely et al. 1999 Levin et al. 2004). Line sepsis, groin infections, and bed sores can be problematic in the transplant recipient as well (Massad 2004). 

Suggested Alternatives for Differential Diagnosis Blastomycosis, coccidioidomycosis, aspergillosis, pneumonia, respiratory distress syndrome, mediastinal cysts, mycoplasma infections, Pancoast syndrome, sarcoidosis, tuberculosis, lung abscess, lung cancer, lymphoma. 

It is not uncommon to find pancreatic pseudocysts after an episode of traumatic pancreatitis or chronic pancreatitis, and some pseudocysts complicating hemolytic uremic syndrome or mediastinal pseudocysts have been reported. CT will reveal a round hypodense structure with a thin or thick wall, which may enhance after contrast injection. Some of these pseudocysts can cause complications, presenting with obstruction of the common bile duct, infection, abscess formation, rupture of the pseudocyst, and can be responsible for splenic vein thrombosis or splenic hemorrhage. CT is the primary imaging tool to visualize and identify these complications (Geier et al. 1990). 

Fig. 27.14. Three weeks after local radiation for a tumorous spine destruction, this patient suffered from fever and dyspnoea. Perihilar infiltrates appeared suddenly. Intralobular septa, consolidation, and ground-glass opacification were determined at HRCT. Especially the para-mediastinal distribution of the infiltrates led to the differential diagnosis of radiation pneumonitis. After failure of antibiotic escalation (chosen because of a concomitant abscess), steroids were applied additionally. This led to a quick improvement of the symptoms as well as reduction of infiltrates...

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