Case Report: Contrast-enhanced ultrasonography for evaluating a newly detected contralateral pulmonary lesion during non-small cell lung cancer chemoimmunotherapy

BackgroundNew pulmonary lesions arising during chemoimmunotherapy for non-small cell lung cancer (NSCLC) pose a common diagnostic dilemma because they may reflect tumor progression, infection, treatment-related inflammation, or other benign processes. Computed tomography remains central to surveillance, but morphology alone is sometimes insufficient for confident characterization.

Contrast-enhanced ultrasonography (CEUS) can provide real-time perfusion information in peripheral pulmonary lesions and may offer incremental value in selected subpleural lesions.Case presentationA 78-year-old man with stage IIIB squamous NSCLC received four cycles of paclitaxel plus cisplatin combined with pembrolizumab. During treatment, he developed a newly detected contralateral lesion in the posterior basal segment of the left lower lobe.

Transthoracic lung ultrasonography demonstrated a subpleural hypoechoic lesion measuring approximately 2.4 × 2.2 cm. CEUS showed rapid hyperenhancement in the pulmonary arterial phase, relatively homogeneous internal enhancement, and slight persistent hyperenhancement in the venous phase, favoring an inflammatory rather than a malignant lesion.