Venous malformation of the foot: Spontaneous regression postpartum on MRI

Venous malformations (VMs) are present at birth, grow proportionally during childhood, and usually do not regress. We report the imaging appearance of a VM of the foot found during pregnancy, which regressed spontaneously postpartum. A 35-year-old, 8-month-pregnant woman presented with a 6-month history of painful swelling of the left foot. MRI demonstrated a well-defined, intricate-shaped mass measuring 38 × 36 × 28 mm between the muscles and tendons of the third, fourth, and fifth toes with subcutaneous extension. Dynamic CT taken a month after delivery revealed gradual enhancement of the lesion. Gray-scale ultrasonography (US) showed a heterogenic hypoechoic mass containing thrombi with venous waveforms on Doppler US. A second MRI obtained 15 months after delivery showed a remarkable reduction of the lesion size (16 × 20 × 15 mm). Symptomatic VMs found during pregnancy can be observed conservatively without treatment.