Detailing the human tail

Experience with human tail and its outcome

There are some common genetic heritages between human and mammals. Human tail, though rare is one of the most noticeable. Till the date, around 60 cases reported in the literature. A true human tail is a benign vestigial caudal cutaneous structure composed of adipose, connective tissue, muscle, vessels and nerves. A true human tail can be distinguished from a pseudotail as the latter is commonly associated with underlying spinal dysraphism, which requires specialised management. We report a case series of four caudal appendages. Two clients were infants, while others two were toddler and presented with cutaneous appendage arising from the lumbosacral region. Out of four, only one had associated spinal dysraphism and neurological manifestation while others did not have spinal dysraphism and neurological manifestation. The appendage was removed by the surgical excision. Clinicians should emphasise the use of 'true tail' and 'pseudo-tail' as the specific disparate terms as the clinical, radiological and histological findings of these conditions differs significantly, along with the management strategies and outcomes.

Classification of the "human tail": Correlation between position, associated anomalies, and causes

INTRODUCTION

Numerous case reports have indicated that the "human tail" is not always a harmless protrusion but can be associated with anomalies such as occult dysraphic malformations. However, the definition and classification of this anomaly have not been discussed. A prevailing hypothesis is that the "human tail" is a residual embryonic tail. Herein, we attempted to classify and define the human tail and investigate the frequency of this anomaly.

MATERIALS AND METHODS

We first defined the human tail as a protrusion on the dorsal side of the lumbar, sacrococcygeal, and para-anal regions identified after birth. We collected case reports written in English, Japanese, French, German, and Italian that were published from the 1880s to the present.

RESULTS

We discovered two important findings: (a) the cause of this anomaly may differ even though the "tails" resemble each other closely in appearance and (b) its position tends to be correlated with the type of anomaly and its associated cause. We propose a new classification of the human tail based on these findings.

CONCLUSION

Our classification may facilitate more accurate treatment and precise case descriptions of the human tail.

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.

Eco-evo-devo: the time has come

The major goal of ecological evolutionary developmental biology, also known as "eco-evo-devo," is to uncover the rules that underlie the interactions between an organism's environment, genes, and development and to incorporate these rules into evolutionary theory. In this chapter, we discuss some key and emerging concepts within eco-evo-devo. These concepts show that the environment is a source and inducer of genotypic and phenotypic variation at multiple levels of biological organization, while development acts as a regulator that can mask, release, or create new combinations of variation. Natural selection can subsequently fix this variation, giving rise to novel phenotypes. Combining the approaches of eco-evo-devo and ecological genomics will mutually enrich these fields in a way that will not only enhance our understanding of evolution, but also of the genetic mechanisms underlying the responses of organisms to their natural environments.

Human tail: nature's aberration

Human tail refers to a congenital cutaneous appendix protruding from the lumbosacral region. It is usually associated with an underlying spina bifida occulta, a form of spinal dysraphism. A contiguous fibrolipoma can sometimes be seen extending from the subcutaneous portion of the tail into the inferior spinal cord, resulting in tethered cord syndrome. Management of such lesions includes complete neurologic examination and magnetic resonance imaging. Early diagnosis and microsurgical intervention can prevent development or progression of severe neurologic defects in later life.

Imperforate anus with a rectovestibular fistula and pseudotail: a case report

INTRODUCTION

Human tails and pseudotails are rare sacrococcygeal lesions that are associated with a wide variety of anomalies and syndromes. Anorectal malformations are also relatively uncommon congenital defects that often occur in conjunction with syndromes or other congenital abnormalities. The anomalies associated with both disorders determine the timing and approach to surgical correction. We present an unusual case of a patient with both imperforate anus and a pseudotail in the absence of a syndrome or other associated anomalies and we emphasize the necessity of a thorough preoperative evaluation.

CASE PRESENTATION

A Caucasian girl was born at term after an uncomplicated pregnancy and was noted at birth to have a skin-covered posterior midline mass and imperforate anus with a fistula to the vaginal vestibule. Ultrasound and magnetic resonance imaging revealed a predominately fatty lesion without presacral extension and ruled out associated spinal and cord abnormalities. The patient underwent diversion with colostomy and a mucous fistula in the newborn period as a fistulogram demonstrated a long fistulous tract to normal rectum and it was anticipated that anoplasty and resection of the mass would require extensive posterior dissection. The sacrococcygeal mass was removed during posterior sagittal anorectoplasty at the age of six weeks which was determined to be a pseudotail because of the composition of brown fat and cartilage. The patient is now 14 months old with normal bowel function after a colostomy takedown.

CONCLUSION

A comprehensive preoperative assessment and thoughtful operative plan were necessary in this unusual case because of the extensive differential diagnosis for sacrococcygeal masses in the newborn and the frequency of anomalies and syndromes associated with tail variants and imperforate anus. The pediatricians and neonatologists who initially evaluate such patients and the surgeons who correct these disorders must be aware of the potential pitfalls in their management.

Thoracic lipomeningocele associated with diastematomyelia, tethered spinal cord, and hydrocephalus

Accessory human tails are uncommon malformations consisting of meningeal and neural structures and possibly occult spinal dysraphism (pseudotails). The thoracic location of a lipomeningocele constituting a pseudotail is very rare. The authors report the case of a young boy harboring a thoracic dorsal appendage consisting of a lipomeningocele and a dermoid cyst that was complicated by the presence of diastematomyelia, tethered spinal cord, syringomyelia, and mild hydrocephalus. The preoperative moderate ventricular dilation was decompressed by the surgical repair of the spinal malformation and required a specific treatment. The authors discuss the rare association of these clinical entities and conclude that complete spine and brain neuroimaging studies are necessary for the correct surgical planning of this kind of malformation.

Human tail and myelomeningocele

The human tail is rarely reported and is usually associated with underlying spina bifida occulta. A male newborn presenting a caudal appendage (human tail) with skin-covered myelomeningocele and tethered cord is described. Surgical excision of the human tail and repair of the myelomeningocele were performed 3 days after birth. After the operation, the patient had an uneventful convalescence and received follow-up at our outpatient clinic without any neurological sequelae. To our knowledge, no similar case report exists in the literature. Like other skin-related lesions in the lumbosacral area, the present case of caudal appendage with myelomeningocele is only a cutaneous sign of underlying spinal dysraphism since the skin and nerve system are related by their similar ectodermal origin. After excision of the tail and repair of an underlying lesion, long-term follow-up of the neurological status is warranted.

Skin-covered midline spinal anomalies: a report of four rare cases with a discussion on their genesis and milestones in surgical management

BACKGROUND

The differential diagnosis for a dorsal midline mass presenting in a newborn encompasses a wide range of pathological conditions, including spinal dysraphisms, tumoral overgrowths including teratoma and hamartoma, disturbances in regression of fetal tail, and pseudotail formation.

OBJECTIVES

To present (a) three rare cases of human tails and one case of tethered cord due to a midline anomaly resembling part of a human limb, (b) to discuss different kinds of clinical and pathological conditions which may be encountered in such newborns, (c) to hypothesize a theory about genesis of these congenital lesions, and (d) to remind drawbacks in preoperative evaluations and surgical management of these newborns.

MATERIALS AND METHODS

Four newborns with dorsal midline malformations initially diagnosed as heterotopias are presented. Appropriate preoperative investigations and proper surgical interventions leading to resection of the lesions were performed. All four were skin-covered lesions containing well-differentiated cellular elements of fat, vascular, muscular, bony, and cartilaginous origin. Midline spinal dysraphism was detectable both pre- and intraoperatively only in one case in which cord untethering was also performed along with the first surgical intervention. In the other three "tailed cases," midline bone defect could not be detected in the available X-ray films; consequently, simple excision of the tail-like lesions was done. The first patient had to be explored for repeat untethering of the cord after 4 years, but the others have not yet developed any sign of tethering during an average period of 12 years follow-up.

CONCLUSION

Morphological diagnosis of these lesions is not easy, and the attending pediatrician and neurosurgeon should be familiar with the differential diagnosis of such lesions and be prepared for possible time-consuming operation mandatory to achieve total resection of the lesion in a newborn under general anesthesia. Reviewing the possible theories regarding the genesis of such anomalies, it is hypothesized and suggested that all similar cases could have been of hamartomatous origin rather than defects of embryogenesis.

Human tail with noncontiguous intraspinal lipoma and spinal cord tethering: case report and embryologic discussion

Children born with a tail-like appendage have a rare malformation that is frequently associated with abnormalities of the spine and spinal cord. A contiguous fibrolipoma is usually seen extending from the subcutaneous portion of the tail into the inferior spinal cord, resulting in tethered cord syndrome. We present the case of a child born with a tail and intraspinal lipoma that were not contiguous with each other, and were separated by an intact layer of lumbosacral fascia. The tail and lipoma were removed and the spinal cord untethered, and the child is neurologically normal 2 years after surgery. The absence of a contiguous lipoma from the tail to the spinal cord suggests that this condition may be principally caused by a disorder of secondary neurulation and/or regression of the normal embryonic tail bud. The embryology of the lower spine is reviewed and possible etiologies discussed.

Ectopic fingerlike structure in the thoracic region. Case report

The authors present a case of a rare cutaneous lesion resembling a human finger that protruded from the posterior thoracic region of a 7-month-old girl who was examined after the fingerlike protrusion was noted at birth. The protrusion measured 3 cm in length and 1 cm in diameter. It was located at the level of T-12 and was surrounded by angiomatous and lipomatous tissue. A computerized tomography scan demonstrated three bones in the protrusion. including deformities of the T-9 and T-10 and T-11 dysraphism. Magnetic resonance imaging revealed a hyperintense signal on the T1-weighted sequence and a hypointense signal on the T2-weighted sequence, which was visualized at the attachment to the spinal cord from T9-11. After removal of the fingerlike structure and subcutaneous mass, a T10-11 laminectomy and removal of the intradural mass were performed. Histological examination showed that the appendage was composed of nail, three bones, cartilage, and normal skin. This appendage can be recognized not only as a variant type of caudal appendage but as an ectopic finger and fingernail. The authors discuss the developmental differences among the protrusion in the present case and ordinary caudal appendages.

The human tail

The human tail is a congenital anomaly with a protruding lesion from the lumbosacrococcygeal region. A newborn with a tail-like structure over the coccygeal area observed since birth is presented. Lipoma accompanied by tethered spinal cord were found. In reviewing the literature from 1960 to 1997, 59 cases were described. Higher incidences of spinal dysraphism (49.15%) and tethered spinal cord (20.34%) compared with previous reports were evident. This fact plays an important role in understanding the disturbance of development and regression of human tails. A new classification according to whether the anomaly appears in combination with spinal dysraphism is proposed for clinical usage. Preoperative detailed image studies are needed to clarify the possibility of tethered spinal cord syndrome developing in the future and thus prevent it. Magnetic resonance imaging is the modality of choice if available. Long-term follow-up for possible sequelae after operation, especially in cases with spinal dysraphism, is necessary.

Early sonographic findings suggestive of the human fetal tail

The prenatal diagnosis of a human tail was suggested in six fetuses with ultrasound findings of an echogenic protrusion in the lumbo-sacral region. All fetuses were at 14-16 weeks' gestation. The ultrasound findings disappeared in all cases at 22-23 weeks. Dermal abnormalities such as pilonidal sinus, deep dimples, and scarred tissue were found in all six newborns. It is possible that the late regression of the embryonic human tail was the cause of these dermal findings.

True tail in a newborn

Human true tail is a rarely reported anomaly that may have a marked psychologic impact on the patient's family and may be associated with other congenital anomalies. A true tail in a newborn girl is reported, and findings from a review of the literature are summarized. The clinical and pathologic differential diagnoses are discussed, as they might affect the management and prognosis of this congenital malformation.

Myelomeningocele and thick filum terminale with tethered cord appearing as a human tail. Case report

Tail-like caudal appendages may be associated with spinal dysraphism, particularly with spinal lipomas or lipomyelomeningoceles. An unusual case is presented of a patient with a myelomeningocele and a thick filum terminale with tethered spinal cord, which presented with the external appearance of a human tail. A review of the literature reveals that human tails may be associated with dysraphic conditions. Extensive neuroradiological examinations should be performed for all such cases of apparent tails.