Prenatal ultrasound characterization of the suprarenal mass: distinction between neuroblastoma and subdiaphragmatic extralobar pulmonary sequestration.

With the increased routine use of prenatal ultrasonography, subdiaphragmatic masses in the fetus are identified more frequently. Suprarenal masses often are presumed to be neuroblastoma and are removed surgically postnatally. We sought to better understand the natural history of subdiaphragmatic extralobar pulmonary sequestration, and to determine if subdiaphragmatic extralobar pulmonary sequestration can be distinguished preoperatively from neuroblastoma. The literature was reviewed for cases of prenatally diagnosed suprarenal masses that proved ultimately to be either subdiaphragmatic extralobar pulmonary sequestration or neuroblastoma. The distinguishing features of the two lesions were identified and an algorithm was created on the basis of these distinctions. Prenatally diagnosed subdiaphragmatic extralobar pulmonary sequestration is no longer rare, with one case being reported for every 2.5 cases of neuroblastoma. On prenatal ultrasonography subdiaphragmatic extralobar pulmonary sequestration usually is echogenic, is left-sided, and can be identified in the second trimester. Neuroblastoma is most often cystic, right-sided, and identified in the third trimester. In summary, subdiaphragmatic extralobar pulmonary sequestration must be considered in the differential diagnosis of the suprarenal mass identified on prenatal ultrasonography. Using the algorithm which we propose, the correct diagnosis can be determined prenatally in 95% of patients.