HUMAN FETAL (VESTIGIAL) TAIL

 

The human fetal tail is a rare congenital anomaly that has been reported antenatally (1,2). It is believed to be a remnant of the embryonic tail (3).
 

Embryology

 

CLASSIFICATION OF LUMBO-SACRAL APPENDAGES

 

  1. True vestigial tails.
    • Contains muscle, adipose and connective tissue, blood vessels and nerves.
  2. Pseudotails.
    • Represent a variety of caudal appendages and protrusions.

 

ULTRASOUND

 

  • Soft tissue mass.
  • No bone or cartilage is present.
  • No connection to the spinal cord.
  • Spontaneous or reflex movement has been observed.
  • Most present clinically with dimples, skin tags and sinuses (these dermal abnormalities may be as a result of late agenesis of the tail).

 

 

 

 

Video link to small residual human fetal tail

 

 

 

 

 

 

DIFFERENTIAL DIAGNOSIS
  1. Spinal dysraphism.
  2. Sacrococcygeal teratoma.

 

 

REFERENCES

 

  1. Abbot JF, Davis GH, Endicott B et.al. Prenatal diagnosis of vestigial tail. J Ultrasound Med 1992;11:53-55.
  2. Zimmer EZ, Bronshtein M. Early sonographic findings suggestive of the human fetal tail. Prenat Diagn 1996;16:360-362.
  3. Belzberg AJ, Myles ST, Trevenen CL. The human tail and spinal dysraphism. J Pediatr Surg 1991;26:1243-1245.