Pulmonary interstitial cholesterol crystals associated with diffuse lung cysts in adult: a case report and literature review

BACKGROUND Cholesterol pneumonitis or endogenous lipoid pneumonia (ELP) result from the accumulation of endogenous cholesterol esters in the lungs, leading to a fibroblastic interstitial inflammatory process, and may be complicated by a secondary bacterial or fungal infection. Striking features were cholesterol clefts in the alveolar and interstitial spaces and alveolar wall-thickening with lymphocytic infiltrations, which was called pulmonary interstitial and intra-alveolar cholesterol granulomas (PICG). CASE PRESENTATION We report a case of pneumothorax with diffuse lung cysts and pulmonary interstitial cholesterol in a 26-year-old woman. Our case is unique because development of PICG or ELP has been observed in children, but rarely in adult. Most cases could be linked to exogenous sources like inhalation of lipid material or gastroesophageal reflex (GER). In our case, no signs of GER could be discovered. Diffuse lung cysts coexisting with pulmonary interstitial cholesterol crystals are never reported. Additionally, no multinucleated giant cells or granuloma are found pathologically, which make the diagnosis of PICG or lipoid pneumonia difficult. CONCLUSIONS Pulmonary interstitial cholesterol crystals may develop gradually and evenly distributed throughout the entire lung and resulted in severe distortion of the native structure of the lung.