My Medical Reviews

The Birth of a child with a caudal appendage resembling a tail is a very rare abnormality and generates an unusual amount of interest, excitement and anxiety

(1). True human tail is a rare event with fewer than 40 cases reported in the literature
(2). It is defined as a caudal, vestigial, midline protrusion with skin covering a combination of muscle and adipose tissue

Case Report

A 3 kg male Baby delivered was the product of full term pregnancy to 30 years old mother which was her 1st pregnancy, with no history of drug exposure during pregnancy or diabetes mellitus. The general and systemic examination of neonate was essentially normal except for tuft of hair in lower back (Sacrococcygeal) region in midline and a soft tissue tail like mass in the same region just below the tuft of the hair (see figure). Possibility of true neonatal tail verse's pseudotail was considered. The neonate did not have any other congenital anomaly. There was no family history of congenital anomaly. The soft tissue mass in the sacrococcygeal region was tail like, soft, well circumscribed measuring 2.5 cm by 0.5 cm. Radiography and ultrasonography of spine did not show any abnormality. This ruled out the possibility of spinal dysraphisam and parasite fetus (pseudotail).

For confirming the diagnosis of true tail, surgical excision of mass was planned, but very unfortunately it was not carried out as parents refused to give consent.

Discussion

Caudal appendages are unusual malformations and are divided into true tails and pseudotails (lipoma, teratoma, myelomeningocoele and parasitic fetus)(3). Simple surgical excision of true tail has been advocated(4). However, recent reports emphasize the associated midline anomalies that might change the surgical approach in these patients(5-7). It is important to make distinction between true and pseudotail in lumbosacaral region since the treatment and prognosis are different(2).

Pathogenesis & Etiology: remnant of embryonic tail. Fetal tail is a normal feature during embryonic development that should regress by the 8th week. Its persistence has been described beyond the 8th week.

Embryology: During the 5th-6th week, the human embryo has a tail with 10 to 12 vertebrae. Then, it starts to regress, reducing the number of vertebrae by fusion, leaving the vestigial coccyx. By this process, at 8 weeks, it disappears, although the exact moment varies. The persistent tail probably arises from the most distal non-vertebrate remnant of the embryonic tail.

Prenatal Diagnosis: Reported in a few cases.

Associated anomalies: spina bifida (20%), meningocele, lipomeningocele, chondrodysplasia, cleft palate, cutaneous hemangiomas, syndactyly and oligodactyly .

Differential diagnosis: Spina bifida, caudal regression sequence and sacrococcygeal teratomas.

Recurrence: never described.

Management: If diagnosed prenatally, no alteration of management is advisable as, to date, no morbidity or mortality related events have been described in these cases. After birth, a thorough examination, which includes CT-scan or MRI is suggested in order to rule out subtle anomalies prior to surgical removal of the tail.