Epidermolysis bullosa with congenital abscence of the skin and deformity of nailsQ82.2

Rare, congenital, clinically heterogeneous, often severe, autosomal-dominant inherited dystrophic epidermolysis bullosa, characterized by a congenital absence of skin (CAS = cutis aplasia, see below aplasia cutis congenita), especially on the lower extremities. Furthermore, blistering of the skin and mucous membranes occurs. Also congenital is the absence or deformation of the fingers and/or toenails.

Congenital extensive skin loss (CAS) is most commonly associated with recessive dystrophic EB. Differentially, however, other EB subtypes may also present under this phenoytp (Martinez-Moreno A et al 2020). In both autosomal recessive epidermolysis bullosa dystrophica with congenital absence of skin and nail dystrophy (41.4% of cases) and autosomal dominant dystrophic EB (22.8%), mutations are present in the COL7A1 gene (Gruis et al. 1992; Christiano et al. 1996).

In a retrospective review based on 55 publications with 96 patients, epidermolysis always affected the lower extremities, and in 17%, it also affected the upper extremities, trunk, or head (Martinez-Moreno A et al. 2020).

Chancellor et al (1992) described a family in which individuals had four generations of epidermolysis bullosa simplex with congenital localized absence of skin (CLAS). At birth, there was a large erosive area on the right leg and a smaller area on the back of the left wrist and hand. The CLAS areas healed completely by 3 months of age with minimal scarring. The nails were normal at birth.

Zelickson et al (1995) reported affected individuals with persistence of blistering into adulthood. Healing of the CAS areas occurred with mild atrophic scarring and milia formation at the sites of blistering.

Regarding extracutaneous dysplasias, pyloric atresia and ear malformations were the most common.

Ultrastructural analysis of affected skin shows poorly formed anchoring fibrils and clefts below the lamina densa. Immunohistochemical staining localized type IV collagen on the roof of the blister skin.

Staining of type VII collagen showed normal distribution (!) in non-blistered skin.

Prognosis varied depending on the subtype of EB and the presence of additional comorbidities. Aplasia cutis heals in a period of 2 weeks to 6 months. Mortality in autosomal recessive dystrophic EB was 6.8%. In junctional EB with pyloric atresia and CAS, 50% of patients died in the first months of life.

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