"Melting Lymph Node Sign": The Endobronchial Ultrasound Pattern Of Cystic Mediastinal Nodal Metastases.

Cystic change in metastatic lymph nodes occurs in certain types of tumors (ie, papillary thyroid carcinoma and squamous cell carcinoma of the Waldeyer's ring) and it is usually observed in the head and neck region. We report on a series of 6 patients with mediastinal metastasis from lung cancer in whom the endobronchial ultrasound showed that most of the lymph node tissue had "melted," leading to the formation of a single, anechoic, avascular cavity. Besides the unique endobronchial ultrasound pattern, we describe the imaging and pathology findings of this unusual presentation of malignant mediastinal lymphadenopathy to facilitate its recognition.