aplasia cutis is a condition in which localized or generalized areas of skin are absent at birth .
bullous aplasia cutis congenita is a subtype rarely seen in its initial form ; in most cases , it is found as a flat scar once the bullae have already reabsorbed . in some cases , there is underlying neural tube defects .
there are only 17 cases reported in the literature including the one discussed in this paper .
a 2-day - old male infant presented to our dermatology service with a 2-cm tense blister filled with serous liquid located on the vertex of the head [ figure 1 ] .
the diagnosis of bullous aplasia cutis congenita was made , and we recommended conservative management . till now the child has no developmental alterations .
aplasia cutis congenita is a rare condition characterized by the absence of skin and in some cases underlying structures such as bone or dura ( 20%30% of patients ) .
it can present as a localized congenital defect with familial incidence ( usually on the scalp ) or be widespread with less familial incidence .
it has been associated with dysgenic hydrocephaly , extensive unilateral linear epidermal nevus , hemangiomas , and multiple defects .
bullous or membranous aplasia cutis congenita is a clinical subtype of this condition , with extremely few cases reported in the literature ( 17 ) , either because of underreporting or to it being so rare .
the lesions are cystic or bullous at birth and eventually transform into an atrophic , flat scar covered by a thin epithelium , which is how doctors most commonly find aplasia cutis .
many present with a collarette of dark , coarse hair around the defect on the vertex ( collar sign ) .
it probably is not attributable to a single cause but to a combination of genetic factors , teratogens , compromised vasculature to the skin , and trauma .
the increased incidence of lesions on the vertex is considered to be the result of a point of maximum tensile forces during rapid brain growth , inducing disruption of the overlying skin at 1018 weeks of gestation .
some authors have proposed that membranous aplasia cutis congenita is an incomplete type of neural tube defect and may be derived from a similar embryological defect .
first , the collar sign that is a relatively specific marker for cranial neural tube closure defects .
second , the thin epithelial covering resembles that of encephaloceles and meningoceles both clinically and histologically .
finally , membranous posterior cranial closure sites in neural tube defects resemble the findings in membranous aplasia cutis .
the diagnosis is primarily clinical and a biopsy is not needed nor suggested routinely , but characteristically there is an absence of epidermis and dermis and decreased subcutaneous tissue as deep as muscle and fascia .
healed lesions often demonstrate flattened epidermis , proliferation of fibroblasts , newly formed capillaries , and complete absence of adnexal structures .
the diagnosis can be suspected in utero with elevated amniotic fluid alpha - fetal protein levels , positive acetylcholinesterase , and normal ultrasound findings . in all patients with aplasia cutis congenita , a complete obstetric and family history
should be obtained , as well as a medical examination guided by the pattern of the lesions .
management remains controversial , because the location , size , and depth of the defect must be considered .
good results are obtained with conservative treatment in a defect up to 47 cm in size ( silver sulfadiazine or antibiotic ointments ) .
bullous aplasia cutis congenita is an extremely rare or much under - reported type of aplasia cutis .
it is hypothesized to be a form fruste of a neural tube defect . some cases present with a dark hair collar sign or an altered hair pattern surrounding the lesion , which can be even more indicative of an underlying neural tube defect .
 aplasia cutis congenita is a rare condition characterized by the absence of skin and sometimes other underlying structures such as bone or dura . 
 it can be a part of various syndromes and can be associated with multiple genetic diseases , malformation patterns , or a combination of all . 
 it is even considered as a form frustre of a neural tube defect in several literatures . 
 bullous aplasia cutis congenita is a clinical subtype of the condition , with extremely few cases reported in the literature . 
 it presents as a cystic or bullous lesion at birth , which eventually transforms into an atrophic , flat scar covered by a thin epithelium . some cases present with 
 a dark collar hair sign around the lesion , which can be even more indicative of an underlying neural tube defect . 
 management remains controversial and depends on the characteristics of the lesion , but conservative treatment is usually chosen . 
Introduction
Case Report
Discussion