Lymphangiosarcoma is a well-recognized complication of chronic lymphedema. We present a rare case of lymphangiosarcoma in a 34-year-old woman who presented with a mass on her left lymphedematous leg. Her leg had become persistently swollen in the weeks during pregnancy and a clinical diagnosis of lymphedema was made, initially. During the third trimester, she developed an ulcerated mass lesion. MRI and FDG-PET/CT scans were performed after delivery. MRI demonstrated a 6 × 8 × 9.5 cm mass in the left thigh. Biopsy of the lesion was consistent with lymphangiosarcoma. FDG-PET/CT demonstrated the primary lesion and its distant metastases. Copyright © 2010 by Lippincott Williams & Wilkins.