PURPOSE: Mediastinal lymph node recurrence is often times seen in lung cancer patients with poor prognosis. Depending on presentation, it may be treated by palliative radiation, chemotherapy or airway interventions. Ethanol is utilized for ablative therapy for malignancy in the liver, however the effects of ethanol injection to mediastinal lymph nodes are unknown. The aim of our study was to examine the efficacy and the safety of transbronchial ethanol injection into mediastinal lymph nodes and also to determine the optimal volume for injection in a porcine model.
METHODS: The convex-probe endobronchial ultrasound was used for endobronchial ultrasound guided transbronchial needle injection of mediastinal lymph nodes under real-time ultrasound guidance (EBUS-TBNI) in anesthetized Yorkshire pigs. Tripan blue dye (n=1), radiocontrast (n=3) and absolute ethanol (n=3) were used for injection. The spread of the injected radiocontrast was visualized by both fluoroscopy and Cone beam CT. Pigs were sacrificed on day 21 post ethanol injection and gross and histological change of ethanol sclerotherapy was examined.
RESULTS: EBUS-TBNI of 2ml of trypan blue resulted in successful injection into the lymph node without evidence of extranodal leakage. EBUS-TBNI of radiocontrast revealed that more than 2ml of injections resulted in occasional leak into the mediastinum (n=3). Sequential Cone beam CT scans captured lymphatic flow into adjacent lymph node stations 30 minutes after injection. EBUS-TBNI of ethanol resulted in both fibrosis and necrosis of the treated lymph node and inflammation of the surrounding soft tissue (n=3). Neither systemic nor respiratory complications were observed in the survival study.
CONCLUSIONS: EBUS-TBNI of ethanol into mediastinal lymph nodes can be performed safely resulting in fibrosis and necrosis of the target lymph node. EBUS-TBNI could be a potential means of tissue ablation which may allow loco regional control of mediastinal malignancies such as localized mediastinal lymph node recurrence.
CLINICAL IMPLICATIONS: The animal study allows further investigation for the development of EBUS-TBNI ethanol sclerotherapy which may be applicable to localized mediastinal lymph node metastasis.
DISCLOSURE: The following authors have nothing to disclose: Takashi Anayama, Takahiro Nakajima, Harley Chan, Michael Daly, Shaf Keshavjee, Kazuhiro Yasufuku
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