The First documented birth of a baby girl with a 5.7 cm tail in Nuevo León, Northern Mexico

According to a specialized study, there are few such cases reported worldwide in the medical literature.

The birth of a baby with a tail was registered in Nuevo Leon, as reported in the Journal of Pediatric Surgery Case Reports, which analyzed the case.

According to the article, the little girl’s birth was normal: a cesarean section in a rural hospital in Nuevo Leon, with a healthy, non-consanguineous father and mother, who had previously had a child, equally healthy.

According to the study, the mother’s pregnancy did not present any complications, and there was no record of exposure to radiation or teratogens (agents capable of causing a congenital defect).

This congenital anomaly has been described more frequently in males. (Photo: Journal of Pediatric Surgery Case Reports)
This congenital anomaly has been described more frequently in males. (Photo: Journal of Pediatric Surgery Case Reports)

It was not until she was out of her mother’s womb that doctors detected that the newborn had a tail-like structure 5.7 cm long and between 3 and 5 mm in diameter. The limb was located in the intergluteal cleft.

The tail structure was soft, covered with skin and fine hair, and could be moved passively without pain but showed no spontaneous movement. Upon detection, the doctors pinched the limb with a needle, and the baby cried, confirming a nerve connection.

After detecting the anomaly, the doctors began to apply various tests. An X-ray ruled out evidence of anomalies or bony structures within the tail. In addition, an abdominal ultrasound ruled out renal and urinary tract malformations or vesicoureteral reflux.

Likewise, the magnetic resonance imaging did not reveal brain abnormalities, was negative for posterior dysraphism, and presented spinal cord and conus medullaris with normal characteristics. Meanwhile, the auditory and cardiac examination was normal, and the baby was discharged for outpatient follow-up.

Clinical photograph, a human tail in the sacrococcygeal region, just above the gluteal cleft and slightly to the left of the midline (Photo: Journal of Pediatric Surgery Case Reports)
Clinical photograph, a human tail in the sacrococcygeal region, just above the gluteal cleft and slightly to the left of the midline (Photo: Journal of Pediatric Surgery Case Reports)

After reaching the age of two months, the child was reevaluated by the pediatric and general surgery team, who found that the tail had grown 0.8 centimeters, so it was removed, and the affected area was reconstructed by Limberg plasty.

Once separated from the baby’s body, the tail was subjected to further analysis which revealed that the sample contained soft tissue, including fibro adipose tissue, vascular structures, and nerve bundles, covered by skin, with no histopathological alterations.

The little girl was discharged, and no complications were reported during the follow-up.

Human tails, rare cases

According to the case study article, there are few cases of human tails reported worldwide in the medical literature.

This takes into account the classifications proposed in the world of medicine. Different authors have proposed different divisions for human tails or caudal appendages, but the one described by Dao and Netsky in 1984 is still one of the most widely used.

It is divided into true tails and pseudo-tails. True tails are described as those that contain adipose, connective, and muscular tissue but do not contain vertebrae or bony structures. Pseudotails resemble true tails but are a superficial or cutaneous manifestation of underlying structural anomalies, such as lipomas, teratomas, and anomalous prolongation of vertebrae.

In the case presented in Nuevo Leon, it was determined that it corresponds to a true human tail since it was not associated with other malformations. It is also presented in the sacrococcygeal region, the most frequent location to find human tails, although human tails have also been reported in the cervical region.