Lymphangiomatosis is a rare disorder that occurs mainly in children or during the first two decades of life. It is characterized by a diffuse proliferation of lymphatic channels involving the bones, visceral parenchyma, and soft tissue. Most cases of lymphangiomatosis have bone and visceral involvement and usually present with chylothorax, chylous ascites, chylous pericardial effusion, or acute symptoms that are related to the affected organs. The authors experienced two cases that presented with chylothorax and multiple lytic bone lesions. Chest drainage and chemical pleurodesis were performed for treatment of the chylothorax. In one case, lytic bone lesions were found only in the right scapula and bone lengthening with an Ilizarov frame was performed for growth arrest in the right humerus. In the other case, lytic bone lesions were found in both femurs and both humeri, the right tibia, and the right scapula; and were particularly severe in the right tibia and femur. The lytic bone lesion, osteosclerosis, pathologic fracture, and pseudoarthrosis were so severe that weight-bearing was impossible. Internal fixation was performed with an intramedullary nail in the left femur.