A 59-year-old male with chronic obstructive pulmonary disease (COPD) returned to the pulmonary clinic three-years after initial evaluation for bronchoscopic lung volume reduction for a giant left upper lobe bullae. He had moderately severe COPD (FEV1 1.6L, 37%) controlled on inhaler therapy and a greater than 35-pack/year smoking history. Previously, he was deemed a candidate for lung volume reduction. However, declined and was lost to follow-up (Figure 1). On presentation, he denied any decline in his physical capacity for the past three-years. His repeat chest CT scan demonstrated complete resolution of the large left upper lobe bullae. As a result of these findings, we did not recommend any further intervention with regard to the previous bullae. However, recommended annual lung cancer surveillance with low-dose chest CT scan.

Giant pulmonary bullae or vanishing lung syndrome (VLS) is defined by radiographic criteria including presence of giant bullae in one or both upper lobes, occupying at least one-third of the hemithorax and compressing surrounding normal lung parenchyma [1].

The natural history of VLS is unpredictable and is based on case reports and experience forming expert opinion. The leading theory for bullae expansion is air trapping that impedes expiratory air-flow leading to tension and gradual enlargement of the air spaces [2]. Although most bullae enlarge, only three-case reports since 1990 have shown regression of the disease [3][4][5]. These cases report partial regression following instances of airway obstruction (infection, inflammation, etc.); in which, the leading hypothesis is complete isolation of the space leading to shrinkage via air and fluid resorption over time. Notably, this is the first case to demonstrate complete resolution of VLS radiographically.

Usual course for vanishing lung syndrome (VLS) is progression of disease and worsening pulmonary function as measured by FEV1. However, we report a very rare case of VLS that has completely resolved without any intervention.

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