Traumatic pulmonary pseudocysts (TPPs) are under-reported in blunt trauma and rarely reported in penetrating trauma. Little is known about the impact of injury mechanism on the pathophysiology or the risk factors that predispose to worse patient outcomes. We hypothesized that blunt and penetrating TPPs have different clinical characteristics and outcomes.

Computed tomography imaging was evaluated for patients presenting at a level 1 trauma center with confirmed TPP from 2011 to 2018. Diameter was determined by largest dimension of the dominant TPP. Clinical variables and TPP features were compared for blunt versus penetrating trauma by using comparative statistics and multivariable analysis.e

A total of 101 TPP patients were identified (blunt = 64; penetrating = 37). In penetrating TPP, rates of concomitant pulmonary laceration, hemothorax, and pneumothorax, were, respectively, 4.5, 3.1, and 1.4 times higher than for blunt TPP. Concomitant rib fracture was twice as common in blunt TPP as in penetrating TPP (69% versus 32%). For penetrating injury, the risk of complications related to TPP was increased (aOR = 5.3), specifically persistent/recurrent pneumothorax (aOR = 10.4). All deaths resulted from pulmonary hemorrhage (blunt = 3, penetrating = 2). Regardless of mechanism, air-fluid level and hemoptysis correlated with death (p < 0.02) and all patients with hemoptysis required pulmonary intervention (p = 0.0001).

Penetrating TPPs demonstrate a unique pattern of concurrent lung injury and increased complication risk. Importantly, severe hemoptysis and air-fluid level may indicate risk of impending morbidity and mortality regardless of injury mechanism and should serve as an early warning sign for the trauma physician.