A 19-year-old primigravida was referred at 38 weeks because of moderate preeclampsia. Obstetric history was otherwise unremarkable.

The ultrasound examination of the fetal head showed a bright echogenic mass of the left temporo-occipital area. It seemed to be compressed to the uterine wall. No skull bone defects were found.

A C-section was performed and a healthy 3.450 kg boy was delivered. Pediatric examination noted a fluctuating non-pulsatile reddish-colored mass on the occipital area, slightly to the right of the midline. It measured 5 x 5 cm, and surprisingly enlarged when the baby was crying.

So, it is a soft tissue tumor of the head, Differential diagnosis for soft-tissue tumors in the fetal head include:

• angiofibroma
• cystic lymphangioma
• desmoid fibromatosis
• fibromatosis colli
• fibrosarcoma
• fibrous hamartoma of infancy
• fibrous histiocytomas
• hemangiomas
• hemangiopericytoma
• hyaline fibromatosis
• lipoblastomatosis
• lymphangioma
• lymphangiomatosis
• myofibromatosis
• rhabdomyoma
• soft tissue sarcomas
• subcutaneous fat necrosis
• teratoma

Apparently, this mass was connected to the fetal venous circulation. We could tell that only after birth because as the baby cried, the mass enlarged. Thus, it had to be a vascular tumor. In fact, neonatal contrasted-MRI showed communication between the tumor and the transverse sinus, and thus, Sinus pericranii was diagnosed. Complete resection of the lesion was successfully performed at 6 months of age.