Amniotic band: a rare presentation.

Sir,

Amniotic band is a rare congenital malformation attributed to strands of the amniotic sac that separate and entangle digits, limbs, or other parts of the fetus while in utero. Damage depends upon the timing of involvement as well as location and degree of compression of the underlying structures. Range of cutaneous presentation includes isolated clefts of face, lip and palate, misshapen nose, skin tag, digital amputation or mild elephantiasis of an extremity beyond a constrictive band (ainhum). Early amniotic rupture, during first 45 days, leads to most severe malformations like anencephaly, misshapen head, omphalocele or gastroschisis, and severe spinal as well as limb deformities.[1] Distinguishing features from other similar anomalies include, severe spinal deformities, spinal deformity associated with an abdominal-wall defect, asymmetric nature of malformations and defect occurring away from midline.[2]

A 14-year old boy was presented to us with seborrheic dermatitis. We noticed a ring like scarring involving the neck and face. History revealed that this scarring was present since birth and remained static and symptom free thereafter. There was no history of birth trauma, manipulation or any other lesion over the scarring. On examination, the irregular band of depressed scarring involved middle of the neck circumferentially and skin over the left cheek [Figures 1 and 2]. It measured 10 to 20 mm wide and 6 mm deep. Upper margin of the band was hypertrophied, firm in consistency and irregularly overhanging at places [Figure 3]. No systemic abnormality was present.

Figure 1

Left side view of amniotic band involving neck and extending the left cheek

Figure 2

Right side view of the amniotic band. Also there are lesions of seborrheic dermatitis

Figure 3

Amniotic band involving back of neck. Multiple open comedones are visible at the margins

Amniotic band is a rare condition to encounter in dermatological practice. There is no firm evidence of definite role of any of risk factors reported so far.[1] Ethiopathogenesis is still unknown, but there are three main theories.

Widely accepted amniotic disruption (extrinsic) theory was proposed by Torpin in 1965.[3] According to this theory fibrous bands of the ruptured amnion float in the amniotic fluid and encircle and trap any part of the fetus. These bands do not grow with fetus. This leads to compression of various parts of the fetus and disturb normal development. Embryonic dysplasia theory (intrinsic) of Streeter suggests that fetal disruptions resulted from imperfect histogenesis.[4] The normal programmed cell death which occurs during embryogenesis is abnormal in case of amniotic band. This results in abnormal functioning of ectodermal placodes which are involved in the formation of many organs. Vascular disruption theory proposed by Van Allen explains defect genesis due to interruption in blood supply during embryogenesis.[5]

Amniotic band in severe cases need urgent and multispecialty care. Dermatologists see mild cases with cosmetic defects only. So, diagnosis should be kept in mind in all cases of congenital scarring. Interestingly, there was a circumferential band of scarring with no deeper extension in our case. Amniotic disruption appears to be the most plausible theory to explain this. Deformity does not explain any developmental defect, as it is not in any embryonic fusion lines. Moreover, defects do not follow any area supplied by any artery, so vascular disruption is ruled out. Enlargement and overhanging of the upper margin can be explained as a result of damage to the lymphatic vessels due to the amniotic band. Plastic surgery correction is useful, which was done in this case with good results [Figure 4].

Figure 4

Plastic surgery correction of amniotic band