A 17-year-old male presented with pain in his lower-left chest. He had no significant medical history and was previously in good health. He had a fractured ninth left anterior rib and the tenth, eleventh and twelfth ribs were absent, which was thought to be a congenital anomaly. Several months later, he presented again with back pain, an enlarging mass in the lower-left chest wall, erosion of the lateral pedicles of the lower thoracic vertebrae and pleural effusion.Physical examination, chest X-ray, MRI of the spine, incisional biopsy, serial CT imaging of the hemithorax, immunohistochemistry, flow cytometry, and enzyme-linked immunosorbent assays.Gorham's lymphangiomatosis with expression of platelet-derived growth factor receptor-beta and elevated circulating platelet-derived growth factor-BB.Spine stabilization, thalidomide, celecoxib, interferon-alpha2b, pamidronate, zoledronate, thoracotomy, pleurectomy, talc pleurodesis, and imatinib mesylate.