Sacro-coccygeal teratoma

Teratomas form from remainders of the primitive streak that normally degenerate or disappear. They are made of pluripotent cells from that structure and their composition can vary greatly. Bone, hair, teeth, and nerve cells may be present in them. Teratomas are seen three times more often in girls than in boys, can become malignant already in children and, for this reason, must be removed as soon as possible.

Chordoma

The chordoma is a tumor that comes from the remains of the notochord. It can be found either in the head area or in the region of the os sacrum. It appears especially around the 50th year of life and can be benign or malignant.

Caudal dysplasia

This general term comprises a group of syndromes that range from small anomalies in the area of the lower vertebrae to complete fusion of the lower extremities (sirenomelia).

Caudal dysplasia is related to diverse cranial anomalies:

• VATER, comprises vertebral and vascular abnormalities, anal atresia, tracheo-oesophageal fistela, esophageal atresia, renal anomalies and radial dysplasia.

The heterogeneity of these abnormalities precludes a common mechanism of origin. These malformations could be connected with erroneous growth and disturbed migration of the mesoblast cells during the third week.