Fig. 2
Images from a 60-year-old male patient with an enlarged lymph node in the right cervical level IV region, histologically confirmed as reactive hyperplasia. (A) Ultrasound image shows an 18 mm × 10 mm suspicious cervical lymph node (arrow), with a plump shape, uneven cortical thickening, and a narrowed, displaced hilum. The hilum shows a detectable blood flow signal. (B) Contrast-enhanced ultrasound (CEUS) in the early enhancement phase shows uniform high enhancement. (C) In the late enhancement phase, uniform slightly higher enhancement is observed. (D) In the postvascular phase, there is no significant regression, and the lymph node shows sustained uniform enhancement. This persistent homogeneous enhancement throughout the node, without perfusion defects or focal hypoenhancement, meets the criteria we define as the "sunburst sign." This sign is characterized by complete, uniform enhancement ≥ 10 min post-injection, indicating preserved macrophage function and likely benignity. Panels a, b, c, and d correspond to schematic diagrams: (a) two-dimensional image, (b) early enhancement, (c) late enhancement, (d) postvascular phase.
