Plasmacytoid Dendritic Cells and Interferon Levels are Increased in Lymphatic Malformations

OBJECTIVE: Describe the presence of plasmacytoid dendritic cells and type 1 interferon and the activation of interferon signaling pathway in lymphatic malformations. DESIGN: Retrospective case series. MATERIALS: Nineteen lymphatic malformations with matching clinical data were compared to control tissue (normal skin and lymph node). METHODS: Paraffin-embedded tissue was evaluated for plasmacytoid dendritic cells, type 1 interferon, and type 1 interferon signaling with immunohistochemistry and RNA in situ hybridization. Staining results were compared with controls and correlated with clinical data with descriptive statistics and Mann-Whitney tests. RESULTS: Lymphatic malformations had increased staining for plasmacytoid dendritic cells, interferons alpha and beta, and phosphorylated signal transducer and activator of transcription 1 compared with controls (P < 0.05). Significantly increased interferon beta staining was present in recurrent lymphatic malformation tissue compared with nonrecurrent lymphatic malformations. CONCLUSION: Lymphatic malformations have unusual ongoing local immune activation, possibly affecting recurrence.