Transient bullous dermolysis of the newborn.

A black male newborn delivered by cesarean section developed large bullae on his extremities and in other friction areas soon after birth. No significant family history was obtained. The bullae healed rapidly, leaving hypopigmentation but no scars or milia. Occasional new lesions continued to appear for four months but not after. Reexamination 12 months later showed a normal healthy infant with only residual hypopigmentation in some of the previously involved areas. Histologic and electron microscopic examinations revealed a subepidermal bulla that was ultrastructurally a subbasal lamina separation. Collagenolysis and damage to the anchoring fibrils were found to be responsible for this separation. Perifollicular collagen sheath was also damaged, but periductal collagen of eccrine duct was intact. Keratinocytes in the lower epidermis showed large, dilated rough endoplasmic reticulum (RER), which contained electron-dense stellate bodies. The contents of these RER vacuoles were discharged into the papillary dermis through the rupture of the basal lamina. The number and size of RER vacuoles in the lower epidermis correlated with the severity of collagenolysis in the underlying papillary dermis. The outer root sheath keratinocyte in the upper hair follicle contained RER vacuoles, but the eccrine duct keratinocyte did not. We suspected that the RER vacuoles contained proteolytic enzymes, which were responsible for the collagenolysis.