Ultrasound and CT findings of subcutaneous metastases in trunk and pelvis: a comprehensive analysis.

Objective: This study aimed to describe the ultrasound, CT findings, and clinical manifestations of pathologically confirmed metastases involving the subcutaneous fat layer of the trunk and pelvis.

Materials and methods: We included 30 patients with subcutaneous metastases in the trunk and pelvis, verified by ultrasound-guided biopsy. We comprehensively reviewed ultrasound findings of all 30 patients and contrast-enhanced CT findings of 25 patients obtained before biopsy. Medical records were reviewed, including primary malignancy type, presence of coexisting distant metastasis, and detection method leading to biopsy referral.

Results: Most subcutaneous metastases were heterogeneously hypoechoic (86.7%) with well-defined margins (80.0%), lobulated (46.7%) or round-to-oval (40.0%) shape, and vascularity (96.7%). Metastases frequently exhibited no contact (53.3%) or focal contact with deep peripheral fascia, resulting in acute contact angle formation (30.0%). Common CT manifestations included central low attenuation with peripheral rim-like enhancement (60.0%) or well-circumscribed lesion with heterogeneous enhancement (32.0%). Lung cancer (46.7%) was the prevalent primary malignancy. CT was the predominant detection method (56.7%). Coexisting subcutaneous metastases were present in 50.0% of cases, and distant metastases (less subcutaneous metastases) were observed in 90.0% of patients.

Conclusion: This study describes typical imaging findings of subcutaneous metastases involving the trunk and pelvis. CT may play a crucial role in their early detection, and our results may assist radiologists in their diagnosis.