This book provides a comprehensive review of uncommon pleural disorders that are encountered in clinical practice but frequently underrecognized. Each chapter offers an in-depth examination of the pathophysiology, diagnostic approaches, and evidence-based management, with particular emphasis on radiologic imaging and detailed pathology to highlight distinguishing features of these often-misdiagnosed conditions. The book is organized into major sections, including non-neoplastic inflammatory pleural disorders—such as fibrothorax and pleuroparenchymal fibroelastosis; rare etiologies of pleural effusions—including chylothorax, urinothorax, and durapleural fistula; and pleural neoplasms—such as malignant mesothelioma, synovial sarcoma, and angiosarcoma. This is an essential guide and academic reference tailored for clinicians and trainees in pulmonary medicine, internal medicine, thoracic surgery, and related disciplines seeking an up-to-date and practical resource for the diagnosis and management of rare pleural diseases.