A 19-year-old woman with no family history of malformations or genetic disorders attended the ultrasound unit at 30 weeks and had a routine anomaly examination. The following images were obtained during that examination.

This image showed a large heterogeneous mass alongside the fetal head.

This image also show the same mass.

The fetal heart with a normal 4-chamber view.

The fetal abdomen appeared to be normal.

The right shoulder and arm were also normal.

The scan revealed a multilocular heterogeneous mass, mostly cystic, but with a solid component attached to the left axilla, the thorax, the left arm and forearm, keeping the whole limb in sustained abduction throughout all examinations. At this time there was loss of architecture of soft tissues of the left upper limb, but the osseous structure was normal. The color Doppler examination showed moderate blood flow in the solid part of the mass.

At the 37th week she was scanned again and the following images were obtained.

Fetal echocardiography revealed holosystolic AV regurgitation.

The tumor had rapidly increased in size, extended to the left lateral wall of the abdomen. The bones of the left upper extremity were no longer visible.  Oligohydramnios could also be seen.

The day after the last examination ultrasound the fetus died. A Cesarean section was performed, and a 6200 grams female was obtained.

The differential diagnosis for this fetal soft-tissue tumor are:

• Axillary cystic hygroma: Unilocular or multilocular lymphatic hamartomas ranging in size from several millimeters to 80 mm, containing a clear or cloudy fluid like lymph. They are usually located at the nuchal area but they can also be seen in the axilla. They are sometimes associated with polyhydramnios.
• Neck teratoma: does not involve the axilla or thoracic wall and is usually associated with polyhydramnios.
• Limb-body-wall complex: this anomaly usually involves the fetal thorax and abdomenand it is characterized by a complex, bizarre appearing mass entangled with membranes and containing the eviscerated organs. Limb defects, scoliosis, neural tube and craniofacial defects are usually associated.
• Lymphangiomata: abnormalities of the lymphatic vessels characterized by cysts within soft tissues usually in the nuchal region. These tumors are usually thin walled, purely cystic, and not as heterogeneous as this mass appeared to be.
• Congenital cavernous hemangioma: hemangioma consists of huge vascular beds, and color Doppler flow imaging could depict marked blood flow in the solid part of the mass.
• Proteus syndrome: a disorder which consist of skeletal, hamartomatous and other mesodermal malformations, characterized by asymmetrical focal overgrowth, subcutaneous tumors, hemihypertrophy. The manifestations are highly variable and features may be present at birth but become more apparent with time. This diagnosis was very likely but this fetus did not met the actual diagnostic criteria  developed by the participants of a workshop held in March 1998 at the National Institute of Health.
• Parkes-Weber syndrome: vascular malformations involving upper and lower limbs characterized by a capillary blush, warmth and underlying arteriovenous shunt. This fetus had no lower limb manifestations.
• Mafucci syndrome: characterized by multiple enchondromata and venous vascular malformations, which can occur anywhere but most commonly in the hands; long bone involvement is common and leads to progressive skeletal deformity and pathological fractures. This fetus had no osseous tumors. The location of this tumor is not the common location for Mafucci syndrome.Color Doppler examination was not consistent with the diagnosis.
• Klippel-Trenaunay-Weber syndrome: This is a rare congenital soft-tissue anomaly which is characterized by the presence of multiple hemangiomata, asymmetric limb hypertrophy and arteriovenous fistulas. This syndrome has a similar ultrasonographic appearance to the vascular lesions with hemangiolymphangioma but the latter is not associated with asymmetric limb hypertrophy or other hemihypertrofic syndromes.

In this case, the tumor turned out t to be an axillary hemangiolymphangioma.