The YAP signaling pathway promotes the progression of lymphatic malformations through the activation of lymphatic endothelial cells.

BACKGROUND: To investigate whether the YAP/TAZ (Yes-associated protein/transcriptional coactivator with PDZ binding motif) pathway contributes to the pathogenesis of lymphatic malformations (LMs). METHODS: YAP, TAZ, CTGF (connective tissue growth factor), and Ki-67 were detected in LMs by immunohistochemistry. The colocalization of YAP and Ki-67 was analyzed by double immunofluorescence. Pearson's correlation and cluster analyses were performed to analyze the relationships between these proteins. Human dermal lymphatic endothelial cells (HDLECs) were used for mechanistic investigation. Rat models of LMs were established to investigate the role of the YAP pathway in LM development. RESULTS: Compared with those in normal skin, the expression levels of YAP, TAZ, CTGF, and Ki-67 were significantly upregulated in lymphatic endothelial cells (LECs) of LMs. Interestingly, YAP and CTGF presented much higher expression levels in infected LMs. In experiments in vitro, lipopolysaccharide (LPS) enhanced the expression of YAP in a concentration- and time-dependent manner via the increased phosphorylation of Erk1/2 (extracellular signal-regulated kinase 1/2). Moreover, the proliferation, invasion, and tubule formation of HDLECs increased significantly in accordance with the activation of the YAP signaling pathway. Furthermore, LM rat models validated that LPS facilitated the development of LMs, which was dependent on the activation of YAP. CONCLUSIONS: The data reveal that activation of the YAP signaling pathway in LECs may play a crucial role in the progression of LMs. IMPACT: Compared with that in normal skin, the YAP signaling pathway was activated in LECs of LMs. Inhibiting the YAP signaling pathway attenuated the proliferation, invasion, and tubule formation of HDLECs. Additionally, the activation of the YAP signaling pathway could promote LM development in a rat model. Activation of the YAP signaling pathway in LECs may play a crucial role in the progression of LMs. The YAP signaling pathway was activated in LMs. Inhibition of the YAP signaling pathway could promote regression of the lesions.

Bipolar radiofrequency plasma ablation (Coblation) of lymphatic malformations of the tongue.

OBJECTIVE: To describe the removal of lymphatic malformations of the tongue using bipolar radiofrequency plasma ablation. METHODS: We report a retrospective case series at a tertiary care academic children's hospital. Three children with lymphatic malformations of the tongue causing symptomatic pain, bleeding and difficulty eating were treated with bipolar radiofrequency plasma ablation (Coblation). Two children had previously undergone wide local excision, both of whom experienced rapid multifocal recurrences. Using the bipolar radiofrequency plasma ablation wand, each lymphatic malformation was ablated to the submucosal surface of the tongue. In all three children, healing occurred by secondary intention. RESULTS: All three children were able to resume a regular diet and were discharged from the hospital by post-operative day 1. After a minimum 6 months follow-up, none of the lesions have recurred and none have required additional treatment. One child has a palpable scar in the central portion of the tongue, where the previous wide local excision had been closed with sutures. She remains asymptomatic without complaints. There were no complications in any child. CONCLUSIONS: Bipolar radiofrequency plasma ablation (Coblation) may provide a safe, simple and effective technique for removal of lymphatic malformations of the tongue in children.