de intensivist

A 78-year-old female cyclist was admitted to the emergency department after a motor vehicle accident (30 km/h). She was intubated at the scene because of decreased consciousness with a dilated left pupil. She was otherwise stable. On admission the chest X-ray showed multiple right-sided rib fractures, pneumothorax and a sharp demarcated opacity projecting over the right lower lung field (figure 1A). The CT-scan confirmed these findings and the opacity was described as a sharp demarcated fluid containing collection (10HU), possibly loculated pleural effusion with a narrow relationship with the thoracic wall (figure 1B). Other pathological findings were a left-sided subdural hematoma, limited subarachnoid blood without mass effect and maxillofacial injury. A chest tube was inserted to drain the pneumothorax and the patient was admitted to the ICU.

Figure 1 A: Chest X-ray showing multiple right-sided rib fractures, pneumothorax and a pericardial cyst (PC) projected as a sharp demarcated opacity projecting over the right lower lung field. B: CT-scan of the same patient showing a right-sided pneumothorax and a pericardial cyst with close anatomical relation with both the chest wall (*) and the pericardium (†)

The origin of the fluid collection and its relation with the sustained injury was unclear at that moment. With the intention of performing transthoracic diagnostic paracentesis, we performed ultrasonography of the right chest wall in left lateral position to determine the anatomic location of the collection. However, contrary to what would be expected from the CT-scan, only normal lung sliding was visualized and it was judged that transthoracic paracentesis could not be performed in a safe manner. Point-of-care cardiac ultrasonography revealed a fluid collection with a narrow relationship with the right atrium (figure 2). Next day, on review of the CT-scan, the fluid collection was reported to be a pericardial cyst.

Figure 2 Still image of transthoracic ultrasonography, subcostal view – notice the narrow relationship of the pericardial cyst (PC) with the right atrium (RA). LA: left atrium

Two important factors rendering the structure invisible to ultrasonography were identified in this patient. First, placement of a chest tube relieved the pneumothorax and may have contributed to interposition of normally aerated lung tissue. Second, the left lateral position may have caused the cyst contents to move freely to the dependent side of the body away from the chest wall.

Pericardial cysts are rare and its estimated incidence lies around 1 in every 100.000 patients. In general, pericardial cysts are of congenital origin and the majority of patients are asymptomatic and therefore diagnosed by incident. However, the cyst can have a significant mass effect on adjacent organs and therefore can cause wide range of symptoms. Depending on the organ this may range from dyspnea, chest pain, arrhythmias, syncope, cardiac tamponade or obstruction, respiratory tract infections and airway obstruction. Treatment of pericardial cysts may range from expectative management or follow-up to surgical resection or cyst aspiration.

For our patient no immediate intervention was considered as she experienced no (previous) symptoms and cardiac ultrasound showed no signs of abnormal filling (specifically, no restrictive inflow pattern). A follow-up CT-scan to evaluate the cyst was planned 6 months after discharge. The scan has not been performed because the patient’s health by that time remained severely impaired by the neurological sequelae of her injury.

Pericardial cysts may mimic loculated pleural effusion as in this patient. Patient positioning and therapeutic interventions may significantly alter orientation and morphology of the cyst.

Disclosures

All authors declare no conflict of interest. No funding or financial support was received.

Written informed consent was obtained from the patient for the publication of this case report (and the accompanying images).