This fetus has 3 examinations spanning the late second and third trimester (note the positions of the stomach). There are two distinct pathologies in these images.

First examination.

Second examination (2 weeks later). 

Third examination (4 weeks after the first exam).

Findings

1. There is clearly a placental mass and it is vascular. Little differential diagnoses here: this is a typical chorioangioma
2. The other finding is of a vascular mass inferior to the heart and anterior to the stomach. This is highly characteristic of a liver hemangioendothelioma.

Hemangioendothelioma may present with the following: 

• elevated maternal serum alpha-fetoprotein level 
• cardiomegaly from high-output cardiac failure 
• hepatomegaly 
• a hepatic mass 
• dilated intrahepatic vessels

The association with chorioangioma ^1,2 or other placental lesions has been reported⁴.

Other primary liver tumors that could have been differential diagnosis include:

• hepatoblastoma, 
• infantile hemangioendothelioma, 
• mesenchymal hamartoma, 
• undifferentiated (embryonal) sarcoma, 
• hepatocellular carcinoma,

Treatment of the hemangioendothelioma may involve³:

• medical management (steroids, furosemide and alpha-interferon) or 
• interventional modalities (hepatic artery ligation or embolization, resectional surgery, or orthotopic liver transplantation).

So the final diagnoses were chorioangioma and hemangioendothelioma

References:

1) Meirowitz NB, Guzman ER, Underberg-Davis SJ, Pellegrino JE, Vintzileos AMHepatic hemangioendothelioma: prenatal sonographic findings and evolution of the lesion.J Clin Ultrasound 2000 Jun;28(5):258-63 

2) Marton T, Silhavy M, Csapo Z, Szende B, Papp Z Multifocal hemangioendothelioma of the fetus and placenta. Hum Pathol 1997 Jul;28(7):866-9 

3) Daller JA, Bueno J, Gutierrez J, Dvorchik I, Towbin RB, Dickman PS, Mazariegos G, Reyes J Hepatic hemangioendothelioma: clinical experience and management strategy. J Pediatr Surg 1999 Jan;34(1):98-105

4) Kanai N, Saito K, Homma Y, Makino S Infantile hemangioendothelioma of the liver associated with anomalous dilated and tortuous vessels on the placental surface. Pediatr Surg Int 1998 Mar;13(2-3):175-6