Lymphangiomatosis originates from congenital multiple malformations of the lymphatic vessel system. It is a benign lesion with malignant behavior. No radical treatment is indicated for this disease. The first patient presented initially with multiple bone cysts suggestive of multiple myeloma, the second with pleural effusion, and the third with mild shortness of breath. The lesions in these 3 patients were mainly located in the upper mediastinum, the parietal pleura, and the lung, respectively. Without any further treatment, their symptoms and radiographic images showed no progression of these conditions after a follow-up time of 7 to 42 months.