Abstract
A case of occipital dermoid cyst was presented, which looked like a encephalocele in naked eye appearance. This male baby was born after normal delivery, and no other anomalies were seen except for an occipital soft mass. It was a slightly relaxed spheric mass and its size was 6.5 × 6.5 × 5 cm in diameter. The base of tumor was slightly constricted. On the surface of tumor, hair was scanty, but covered with normal skin. Fluctuation was present. There was no pulsation or expansion on crying. Plain skull X-ray showed a small and round bone defect which was considered as a canal perforating the occipital bone obliquely and inferiorly in Towne projection. On CT scan, the fluid in the cyst showed almost same density as the cerebrospinal fluid in the ventricle. At the operation, a semi-translucent cyst wall containing slightly turbid yellowish fluid (90 ml) was found under the scalp. At the bottom of the cyst, there was small mass which contained hair and had the stalk extending into the epidural space through the bone defect. Histological examinations disclosed the dermoid cyst. While examining the huge occipital soft mass in a new-born baby, it is difficult to make a differential diagnosis either occipital encephalocele (meningocele) or dermoid cyst under the naked eye appearance or even by CT scan. However plain skull film of occipital encephalocele are usually characterized with relatively large and round bone defect at occiput. On the other hand, bone defect of the dermoid cyst at occipital area is small and runs obliquely and inferiorly. These plain skull X-ray findings would give a much help for the precise diagnosis of new-born occipital soft mass.
