Definition
• Localized (lymphangioma) or diffuse (lymphangiomatosis) proliferation of thin-walled lymphatic vessels lined by endothelial cells
Pathogenesis
• Largely unknown; some may be a developmental abnormality, whereas others are neoplastic
Clinical features
Epidemiology
• Very rare
• Lymphangiomatosis is often diagnosed in children or young adults
Presentation
• Wheezing, dyspnea, pleural effusion, hemoptysis or can be asymptomatic
Prognosis and treatment
• Severity and prognosis depend on the extent of lung involvement
• Surgical excision for localized lesions
• Lung transplantation has been reported for diffuse lymphangiomatosis
Pathology
Histology
• Proliferation of thin-walled, anastomosing lymphatic vessels lined by a single layer of endothelial cells lacking cytological atypia
• Filled with clear or light eosinophilic fluid
• Lymphangiomatosis often follows the normal lymphatic routes in distribution: subpleural, perivascular, peribronchial, or along interlobular septa
Immunopathology/special stains
• CD31 labels endothelial cells
• D2-40 is more specific to lymphatic endothelial cells
Main differential diagnoses
• Pulmonary lymphangiectasia
• Lymphangioleiomyomatosis
• Other vascular proliferations or malformations
Fig 1 Lymphangioma and lymphangiomatosis. Low power: increased number of complex, thin-walled vascular spaces.
Fig 2 Lymphangioma and lymphangiomatosis. High power: endothelial cells at the lining; clear lumen with no red cells; delicate collagen in the wall.
Fig 3 Lymphangioma and lymphangiomatosis. D2-40 immunohistochemical stain highlights lymphatic endothelial cells.