Swyer–James–Macleod syndrome mimicking an acute pulmonary embolism: a report of six adult cases and a retrospective analysis

Background and Aim In patients with pulmonary embolism (PE), a pulmonary radiograph may reveal oligemic fields (the Westermark sign) associated with sites of occlusion of the pulmonary arteries, interruption or loss of the artery line (the knuckle sign), and even unilateral hyperlucency attributable to reduced overall lung vascularity. In Swyer–James–Macleod syndrome (SJMS), which develops as a result of bronchiolitis obliterans, unilateral hyperlucency is evident because of emphysema and hypoplasia of the pulmonary artery and its branches. Therefore, SJMS cases with clinical and laboratory data compatible with PE may in fact be confused with PE. The cases of six adult patients who were initially presumed to have PE but on further investigation were diagnosed with SJMS are presented in this report, which thus can serve as a guide for diagnosis of similar cases in future. Methods We studied six adult patients who presented with dyspnea. Their pulmonary radiographs revealed lobar/unilateral hyperlucency and PE was initially suspected. The pulmonary artery and branches thereof exhibited parenchymal emphysema and hypoplasia, and we thus diagnosed SJMS. Results We studied 4 males and 2 females with a mean age of 51 years (range, 20–73 years). Left lung involvement was evident in five cases. Conclusion Unilateral hyperlucency may be a feature of both PE and SJMS. Although these conditions are very different, both present similarly in radiographic terms and may be easily confused when the clinical data and the anamnesis raise a suspicion of PE, causing unnecessary testing and treatment.