AbstractBackgroundKaposiform lymphangiomatosis (KLA) has recently been distinguished as a novel subtype of generalized lymphatic anomaly (GLA), and is characterized by foci of spindle endothelial cells amid a background of malformed lymphatic channels. The etiology of these diseases remains unknown and diagnosis is confounded by their similar clinical findings. This study aimed to clarify differences in the clinical findings and plasma cytokine profiles of GLA and KLA patients.ProcedureClinical features data of GLA and KLA patients were obtained from a national survey. Differences in clinical findings, plasma levels of cytokines, and survival were analyzed. Plasma was obtained from healthy controls and GLA and KLA patients. Thirty‐six angiogenic and lymphangiogenic factors were evaluated for cytokine concentration.ResultsTwenty‐one patients with GLA and 11 with KLA were recruited. Mediastinal masses, hemorrhagic pericardial and pleural effusion, coagulation disorders, and thrombocytopenia were more frequent in KLA than in GLA. KLA had a significantly poorer outcome than GLA (P = 0.044). Soluble VEGFR3, angiopoietin 2, HGF, soluble HER2, tenascin C, and soluble HGFR levels were higher in KLA. Notably, soluble VEGFR3 and angiopoietin 2 levels were approximately 10‐fold higher than those of other molecules measured. However, soluble VEGFR1 and soluble TIE2 were lower in KLA than in GLA and the controls.ConclusionsPatients with KLA have an unfavorable prognosis and serious symptoms (hemorrhagic pleural effusion and coagulation disorders). Our data indicate that eight angiogenic cytokines might be potential biomarkers of KLA.