Human tail: nature's aberration

A True Human Tail In A Neonate Born In Saudi Arabia: A Case Report

A caudal cutaneous appendage known as the true human tail is a rare and benign condition. Different classification systems have been established, mostly based on the presence of associated spinal dysraphism. Imaging studies play an important role in detecting the prognosis and developing a management plan. Here, we present a rare case of a true human tail with no underlying spinal dysraphism in a preterm neonate.

Atavistic and vestigial anatomical structures in the head, neck, and spine: an overview

Organisms may retain nonfunctional anatomical features as a consequence of evolutionary natural selection. Resultant atavistic and vestigial anatomical structures have long been a source of perplexity. Atavism is when an ancestral trait reappears after loss through an evolutionary change in previous generations, whereas vestigial structures are remnants that are largely or entirely functionless relative to their original roles. While physicians are cognizant of their existence, atavistic and vestigial structures are rarely emphasized in anatomical curricula and can, therefore, be puzzling when discovered incidentally. In addition, the literature is replete with examples of the terms atavistic and vestigial being used interchangeably without careful distinction between them. We provide an overview of important atavistic and vestigial structures in the head, neck, and spine that can serve as a reference for anatomists and clinical neuroscientists. We review the literature on atavistic and vestigial anatomical structures of the head, neck, and spine that may be encountered in clinical practice. We define atavistic and vestigial structures and employ these definitions consistently when classifying anatomical structures. Pertinent anatomical structures are numerous and include human tails, plica semilunaris, the vomeronasal organ, levator claviculae, and external ear muscles, to name a few. Atavistic and vestigial structures are found throughout the head, neck, and spine. Some, such as human tails and branchial cysts may be clinically symptomatic. Literature reports indicate that their prevalence varies across populations. Knowledge of atavistic and vestigial anatomical structures can inform diagnoses, prevent misrecognition of variation for pathology, and guide clinical interventions.

A human tail arising from the anal mucocutaneous junction: A case report

Introduction

Human tails are rare congenital malformations that describe protrusions commonly located around the midline of the lumbosacral region covered by skin, representing an embryonic remnant. Human tails are broadly classified into true and pseudo-tails. The real ones represent the persistence of a remnant of the embryonic tail formed between the fourth and eighth week of gestation.

Presentation

A male infant aged 42 days presented to our institution with a tail-like structure that originated from the anal mucocutaneos junction. The parents did not bring the baby at birth because of the social stigma and ignorance. On examination, there was a tail-like structure that is about 22 cm in length and 1.5 cm in diameter originated from the mucocutaneous junction at the anus at the left side. There was no bony element on palpation. The lower vertebral column examination showed no abnormalities, and this was confirmed with an x-ray. The patient was operated on with simple excision of the tail and primary closure of the wound at the base. He was discharged on the same day well and good. The tail was taken for microscopic histopathology.

Discussion

There are few reported cases describing human tails. However, none of them was originating from the anal mucocutaneous junction.

Conclusion

We report the first case of a human tail arising from the anal mucocutaneous junction worldwide. Due to its very superficial origin, it was not associated with any other anomalies.

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Human tails are rare congenital protrusions located commonly around the midline of the lumbosacral region

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It is the first reported case worldwide of a human tail arising from the anal mucocutaneous junction.

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We performed a simple excision of the tail and a primary closure of the defect and the tail was sent for histopathological examination

Limited dorsal myeloschisis with a contiguous stalk to human tail-like cutaneous appendage, associated with a lipoma of conus medullaris: A case report

INTRODUCTION

Limited dorsal myeloschisis (LDM) is a recently described pathological entity, characterized by a defect of the closed focal neural tube and a fibroneural pedicle connecting the cutaneous lesion to the spinal cord.

PRESENTATION OF THE CASE

This case describes a 9-month-old child with a human tail and an underlying spinal dysraphism. This was represented by LDM stalk associated with a medullary lipoma, in connection with the dorsal cutaneous appendage. We also report the therapeutic proposal for this case and its clinical outcome.

DISCUSSION

LDM is a distinctive clinicopathological presentation of a spinal dysraphism, associated with numerous anomalies, such as lipomyelomeningocele, tethered cord, lipoma, congenital heart disease and teratoma. In this case, surgical treatment for LDM consists of surgical resection of the appendage, untethering of the spinal cord and resection of conus medullaris lipoma in the same procedure.

CONCLUSION

In this case report, we share the experience of a referral service in pediatric neurosurgery regarding clinical and radiological diagnosis, and the successful treatment of this rare type of congenital malformation. Therefore, clinicians should be aware of possible morphological variations of the skin lesion associated with LDM.

A True Human Tail in a Neonate: Case report and literature review

A true human tail is a benign vestigial caudal cutaneous structure composed of adipose, connective tissue, muscle, vessels, nerves and mechanoreceptors. A true human tail can be distinguished from a pseudotail as the latter is commonly associated with underlying spinal dysraphism, which requires specialised management. True human tails are very rare, with fewer than 40 cases reported to date. We report a healthy one-day-old male newborn who was referred to the Bharath Hospital, Kottayam, Kerala, India, in 2014 with a cutaneous appendage arising from the lumbosacral region. Magnetic resonance imaging of the spine ruled out spinal dysraphism. The appendage was removed by simple surgical excision. Clinicians should emphasise use of 'true tail' and 'pseudotail' as specific disparate terms as the clinical, radiological and histological findings of these conditions differ significantly, along with management strategies and outcomes.

Proposed caudal appendage classification system; spinal cord tethering associated with sacrococcygeal eversion

INTRODUCTION

The most commonly used classification system for caudal appendages (aka human tails) dates from the 1980s and classifies appendages (tails) as either true tails or pseudotails. Advances in neuroimaging since the 1980s, however, as well as an ever-increasing number of reported cases, have made this system outdated. Sacrococcygeal eversion is a condition in which the distal sacral and coccygeal vertebrae are curved in a retroverted rather than anteverted direction. It can give rise to one type of caudal appendage. Sacrococcygeal eversion has never been associated with spinal cord tethering in any previously published reports.

METHODS

We reviewed all cases of caudal appendage encountered by pediatric neurosurgeons at Children's Hospital Colorado since 2000 in which the appendage would be classified as a true tail by the most commonly used system mentioned above. We also reviewed cases of sacrococcygeal eversion encountered since 2000 by the same group of pediatric neurosurgeons. We searched the hospital electronic medical record system for additional appendages using the terms "caudal appendage" and "persistent human tail."

RESULTS

We found 9 "true" tails (as classified by the most commonly used system). All 9 were associated with tethering or possible tethering of the spinal cord and 6 were associated with a low-lying conus medullaris. There were 8 cases of sacrococcygeal eversion, including 2 associated with Apert or Pfeiffer syndrome and fibroblast growth factor receptor 2 (FGFR2) mutations; these have previously been reported. There was a single case of sacrococcygeal eversion associated with Goldenhar or Turner syndrome; the former was associated with a potentially tethering lesion. Four cases of sacrococcygeal eversion not associated with any known syndrome were also found; two of these were associated with tethering or potentially tethering lesions.

CONCLUSIONS

Most so-called true tails are likely cutaneous markers for spinal dysraphism and spinal cord tethering and are not remnants of the embryonic human tail. Sacrococcygeal eversion can be associated with spinal cord tethering. Based on our cases, and on review of the literature, we devised a five-category classification system for caudal appendages: (1) soft-tissue caudal appendages, (2) bony caudal appendages, (3) bony caudal prominences, (4) true tails, and (5) "other" caudal appendages.