Contrast‐Enhanced Ultrasound in Diagnosing Rare Calf Muscle Metastasis of Lung Cancer: A Case Report With Literature Review

Skeletal muscle metastasis, though rare in lung cancer, can mimic thromboembolic disease. We describe a patient with squamous cell carcinoma who developed bilateral calf swelling postoperatively. While ultrasound revealed right popliteal vein thrombosis, a left calf hypoechoic lesion exhibited marked hypervascularity on contrast-enhanced and microvascular flow imaging, ultimately diagnosed as metastasis. This case illustrates a critical diagnostic pitfall and advocates for contrast-enhanced ultrasound in evaluating ambiguous limb lesions during cancer care.