Differentiating fibroadipose vascular anomaly from suspected venous malformation with core needle biopsy: A case series.

Vascular anomalies, as classified by the International Society for the Study of Vascular Anomalies (ISSVA), include vascular tumors, vascular malformations such as venous malformations (VMs), and provisionally unclassified lesions. Diagnostic overlap between VMs and fibroadipose vascular anomalies (FAVAs) can lead to misclassification and inappropriate treatment. Correct identification of these conditions prior to intervention is essential to reduce healthcare costs and patient morbidity. The purpose of this case report illustrate the diagnostic challenges in differentiating VMs from FAVAs using noninvasive imaging and to highlight the critical role of interventional radiology and histopathology in accurate diagnosis and management. This report presents two cases of lower extremity vascular anomalies with similar clinical symptoms and overlapping imaging findings on ultrasound and noncontrast MRI. Both lesions were initially suspected to be VMs and referred for sclerotherapy. Diagnostic digital subtraction angiography (DSA) and interventional evaluation were performed, with tissue sampling in one case. Patient A underwent successful sclerotherapy following DSA findings consistent with a VM. In contrast, Patient B's DSA demonstrated contrast pooling without venous drainage, prompting a core needle biopsy, which confirmed FAVA. Sclerotherapy was avoided due to the lesion's fibrofatty composition, which renders it less responsive to such treatment. These cases suggest that MRI and ultrasound may be insufficient to distinguish between VMs and FAVAs due to overlapping imaging characteristics. Interventional radiology techniques, including DSA and tissue sampling, are invaluable for definitive diagnosis and treatment planning. Clinicians should maintain a high index of suspicion for FAVA in lesions with atypical imaging findings to avoid mismanagement.