Prenatal diagnosis and management of a fetal neck mass.

We report the case of a benign mesenchymal spindle-cell tumor located on fetal neck, diagnosed during prenatal ultrasound and magnetic resonance investigation. A 30-year-old woman (gravida 2, para 1) was referred to our perinatology unit for evaluation of a fetal neck mass that had been identified on ultrasonography at 29 weeks gestation. A right lateral neck mass was observed (size: 42×40 mm) that extended from the preauricular region to right clavicula. Fetal MRI revealed a solid heterogeneous mass arising from the right lateral neck and there was no invasion around tissue and no extension of the mass into the chest. At 37 weeks after birth, we observed that the mass was subcutaneous and there was no invasion to the surrounding tissue. The trachea was not compressed and there was no extension of the mass into the chest. Then, the neck mass was completely resected after birth without any complications. Histopathological examination of tumor was consistent with mesenchymal spindle-cell tumor. Immunohistochemical staining with CD34 and actin was positive; however, caldesmone, epithelial membrane antigen (EMA), and S-100 was negative. Fetal MRI performed during the pregnancy for investigation of fetal neck masses detected on ultrasound gives compatible results observed in the neonate after birth and maintains adequate findings for follow-up and planning of treatment.