Neurology India Medknow Publications on behalf of the Neurological Society of India ISSN: 0028-3886 EISSN: 1998-4022 Vol. 59, Num. 4, 2011, pp. 637-638

Neurology India, Vol. 59, No. 4, July-August, 2011, pp. 637-638

Letter to Editor

Human tail continuing as transitional lipoma

Pravin Salunke, Sukumar Sura, Manjul Tripathi, Kanchan Mukherjee

Department of Neurosurgery, PGIMER, Chandigarh, India
Correspondence Address: Pravin Salunke, Department of Neurosurgery, PGIMER, Chandigarh, India, drpravin_salunke@yahoo.co.uk

Date of Submission: 27-Feb-2011
Date of Decision: 27-Mar-2011
Date of Acceptance: 11-Apr-2011

Code Number: ni11193

PMID: 21891956

DOI: 10.4103/0028-3886.84360

Sir,

Human tail is a rare congenital anomaly, and many saw this curious condition to be a relic of the human evolution, while others made it the subject of superstition. This dorsal cutaneous appendage is often considered to be a cutaneous marker of underlying occult spinal dysraphism. Advanced imaging in recent decades has allowed a more thorough investigation of these patients and better defined their association with spinal dysraphism and tethered spinal cord. It is rare for the appendage itself to cause tethering, and we report one such case.

A 9-month-old healthy male infant was brought for a "tail-like" structure in the lumbosacral area since birth. According to the parents, the tail was about 5 cm at birth and the size had been increasing with age. On examination, the appendage was 10 cm long and was attached just off the midline to the right side sacral region, resembling a tail. It was soft and non-tender, covered with normal skin [Figure - 1]a. No bony attachment or any voluntary movement was observed in the mass. Neurological examination including anal tone and wink reflex were normal. Magnetic resonance imaging (MRI) of the lumbosacral region revealed a transitional lipoma and a doubtful connection of the lipoma to the external appendage off the midline [Figure - 1]b and c; [Figure - 2]a-c. Intraoperatively, a fibrous tract was seen extending from the base of the appendage intraspinally. This appendage was traced to the defect in the bone and dura, where the tract merged with the transitional lipoma. The tract was severed from its attachment to the lipoma and the lipoma was excised, thereby detethering the cord. The infant recovered uneventfully. Histopathology of the tail showed stratified squamous epithelium and adnexal structures with adipose tissue.

In about 50% of the cases, the appendages were often associated with either meningoceles or spina bifida occulta. The other lesions that are found in the descending order of frequency are lipoma (27%) and tethered spinal cord (20%), with spina bifida (50%) and tethered cord (20%). ^[1] Lipomas, teratomas and gliomas have also been identified as uncommon coexisting pathologies. ^[2] The tail itself may cause tethering as in our patient.

During the 5 ^th -6 ^th weeks, human embryo has a tail comprising of 10-12 vertebrae. This starts regressing, by fusion of vertebrae, leaving the vestigial coccyx. Thus, this embryonic tail disappears by the 8 ^th week. ^[3] In our patient, lipomeningomyelocloele is a defect of primary neurulation, whereas the true tail has its origin in secondary neurulation. The true tail arises from the most distal non-vertebrate remnant of the embryonic tail. It contains adipose, connective tissue, central bundles of striated muscles, blood vessels and nerves, all covered by a layer of skin. It lacks bones, cartilages, notochord and spinal cord. On the other hand, pseudotails are varied lesions with only a superficial resemblance to a true vestigial tail and represent a prominent sacrum, elongated coccyx or an underlying lipoma or a teratoma. ^[3] Apart from this, the true tail is a dermal appendage mostly located in the sacrococcygeal region and can be located 1-1.5 cm to one side. ^[4] The tract connecting the appendage and the cord may pursue an oblique course and hence is often missed on pre-operative MRI as their lie is in different planes.

This patient highlights the importance of screening patients with these appendages or the so-called "tails" for spinal dysraphism. Also, in every case of dorsal cutaneous appendage, a careful search for the intraspinal extension of the lesion should be made and operated upon with that in mind.

References

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