fetal neuroblastoma

Fetal neuroblastoma is a type of congenital neuroblastoma (neuroblastoma arising in utero).

Epidemiology

The estimated incidence is at ~1 in 20,000 births.

Pathology

In the vast majority (~90%) of cases fetal neuroblastomas arise in the adrenal glands. They have been diagnosed as early as 19 weeks of gestation, but usually are seen in the third trimester (with mean age at diagnosis being ~36 weeks).

Location

There may be a right-sided predilection.

Radiographic features

Ultrasound

They are typically seen as a complex mass with cystic components (~50% ) around the expected position of the fetal adrenal gland. Some lesions may appear entirely solid or predominantly cystic.

Color Doppler interrogation often shows diffuse vascularity rather than a single feeding vessel.

Staging

Staging is similar to standard neuroblastoma staging.

Complications

developmental of hydrops fetalis: uncommon but a concerning complication
development of maternal pre-eclampsia

Treatment and prognosis

In almost all cases the tumor undergoes maturation and regression, and prognosis is excellent (in contrast to childhood neuroblastoma) with many institutions recommending conservative management.

Differential diagnosis

For ultrasound appearances consider:

fetal adrenal hemorrhage: no color flow
sub diaphragmatic extra-lobar pulmonary sequestration: classically left-sided and may demonstrate a single feeder vessel