A Rare Case of Faun Tail Nevus Without Any Underlying Spinal Anomaly

Respected Sir,

Faun tail nevus is a rare congenital anomaly where a tuft of hair is present over the lumbosacral region. It is one of the most important neurocutaneous markers for spinal dysraphism and is almost always associated with some underlying spinal anomaly. Neurological deficit may or may not be present in all cases. We report one case of faun tail nevus in a 5 year old girl without any neurological deficit and without any underlying spinal anomaly.

CASE PRESENTATION

A five year old girl presented to our OPD with the complaint of abnormal hair growth over the lower back region. The child has been receiving non-prescription topical Eflornithine application intermittently for over a year from some quack. On presentation, she did not have any neurological deficit. Her clinical examination was also normal. Her MRI showed a normal spinal cord and vertebral column without any anomaly. On examination, she had 16 cm long tuft of hair in the midline over L3,L4 and L5 region with extension over the left paraspinal region. The hairs were terminal and of the same brown colour as that of her scalp hair. There were no pigmentary changes in the underlying skin. She did not have similar lesion anywhere else in the body. The child was advised for epilation with Intense Pulsed Light (IPL) and is currently undergoing the same.

DISCUSSION

Lumbosacral hypertrichosis is said to be common in certain ethnic groups,[1] however, a localized growth of hair is very rare. According to the type of the hair, it can be of three types. Simple nevoid hypertrichosis is when there is a simple tuft of hair away from the midline. If the hairs are sparse and non-terminal, the entity is called silky down. Faun tail nevus, the third type, is comprised of coarse, well formed terminal hair.[2]

During the fourth intrauterine week, the craniocaudal closure of the neural tube occurs. During the process of separation of the neuroectoderm from the surface ectoderm, if any anomaly occurs, it leaves different clefts or marks on the surface ectoderm as well as anomaly in the developing spinal cord due to a common ectodermal origin. Sacral dimples, lipoma, hemangioma, dermal sinuses, telengiectasia, aplasia cutis, meningocele or meningomyelocele etc are some of the known neurocutaneous markers of occult spinal dysraphism.[13] Faun tail nevus is the third most common neurocutaneous marker of spinal dysraphism present in 40–50% of the cases with spinal dysraphism. Arora et al. presented a series of 15 cases of faun tail nevus, all of whom had underlying spinal anomalies. The anomaly is more common in the female gender with very few isolated case reports of presence in male subjects.[3]

In overt cases of spina bifida with neurological deficit, the diagnosis is secondary. Patients mostly undergo treatment for the neurological part and the nevus part is taken care of later. However, in occult cases, patients usually turn up for cosmetic purpose for removal of unsightly tuft of hair over the lumbosacral region. Unusual location in the upper thoracic region has also been reported in two cases. Both cases were associated with spinal anomaly.[45] A complete neurological examination and work-up with magnetic resonance imaging of the spine is warranted in all cases, even those without neurological deficit.[6] More often than not, these cases are associated with some or other form of spinal anomaly. Varied spectrum of spinal anomalies such as spina bifida, diastematomyelia, cord tethering, syrinx, hemivertebra, incomplete vertebra etc have been described.[13] Other associated systemic diseases reported are neurofibroma, aplasia cutis congenita, familial leukodermic darier disease and porphyria.[27] The present case is rare because the occurrence of faun tail nevus was an isolated entity without any spinal anomaly. Literature search revealed only one such case reported previously.[8] Management usually involves correction of the underlying spinal anomaly if possible along with neurological rehabilitation. The tuft of hair can be managed by chemical or laser epilation. Various authors have reported use of different hair removal lasers such as diode, alexandrite or Intense Pulsed Light with variable success.[35,910] The side effects are minimal with superficial burns reported in some cases that heal well with conservative management.

CONCLUSION

Faun tail nevus is a rare congenital entity which is a consistent neurocutaneous marker for spinal dysraphism. However, isolated cases without any spinal anomaly can also occur which requires only hair removal for cosmetic purpose. Proper diagnosis and medically supervised hair removal should be advocated otherwise these patients may fall prey to non-prescription, over-the-counter medications which may have adverse effects.