Kinoshita Y, et al. - Researchers studied the pulmonary lymphatic vessels in pleuroparenchymal fibroelastosis (PPFE), histologically in order to test their hypothesis that PPFE progress was linked with an impaired lymphatic drainage system, resulting in the failed resolution of intra-alveolar exudate. From 1995 to 2017, medical records were retrospectively reviewed. The increase in lymphatic vessel density was found to be associated with the characteristic physiology of PPFE, such as a flattened chest cage on computed tomography and high residual volume/total lung capacity ratio on spirometry among PPFE patients. Supportive characteristic for the differentiation of PPFE from idiopathic pulmonary fibrosis (IPF) and the apical cap was a significant increase in the density and number of lymphatic vessels.