Disseminated lymphangiomatosis and Gorham-Stout disease are being considered as two forms of a single rare disease, characterized by a proliferation of lymphatic vessels, triggered by lymphangiogenic factors. There is no biological marker of the disease. Plasma VEGF might be a useful tool since the recent demonstration of its pivotal role in the mechanism of this disease. A 45-year-old woman with a history of disseminated lymphangiomatosis involving mediastinum, retroperitoneum, spleen and systemic bones for 29 years was treated with Interferon alpha 2b at a dosage of 7.5 to 15 million IU 3 times a week for 5 years. Plasma VEGF quantification was performed twice a year and showed a marked increase before therapy, which normalize after 18 months of treatment with Interferon. The normalization of plasma VEGF is correlated with the clinical improvement objectively appraised by a marked reduction of spleen lesions and significant improvement of the other damages in soft tissues and bones. Thus, we conclude that plasma VEGF determination should be considered for diagnosis and follow-up of the course and the treatment of disseminated lymphangiomatosis-Gorham-Stout disease.