Calvarial venous malformation highlighted by the flow–reflux phenomenon on ultrasound

A case is reported of a woman presenting with a firm, tender right frontal lump. Ultrasound showed a small, irregular subgaleal mass with tiny bone surface perforations. Color Doppler ultrasound demonstrated compression–decompression induced alternating flow signals, indicating flow and reflux through the bone lesion. CT revealed an expansile osteolytic frontal lesion with a honeycomb pattern, consistent with an intraosseous venous malformation, which was confirmed histologically. The added value of compression–decompression color Doppler ultrasound in low‑flow calvarial vascular malformations is illustrated. Teaching point: Compression–decompression color Doppler ultrasound can reveal flow–reflux in low‑flow intraosseous venous malformations, contributing to the diagnosis.