Transient bullous dermolysis of the newborn - Skin
The etiology of TBDN stems from weakly structured anchoring fibrils at the dermal-epidermal junction, causing a separation in the sublamina densa plane and leading to blister formation, which coincides with the pathophysiology of DEB. However, TBDN is distinguished by its self-limiting course and the presence of electron-dense inclusions, called stellate bodies. These appear within dilated rough endoplasmic reticulum of basal and suprabasal keratinocytes. Immunofluorescence and electron microscopy show that these inclusions contain type VII collagen, the key structural protein in anchoring fibrils. Immunofluorescence reveals a granular pattern for type VII collagen in the lower epidermis and a thinned linear pattern at the dermal-epidermal junction, which is considered a distinctive feature of TBDN. The clinical course of improvement seen in most TBDN cases reflects the eventual secretion of type VII collagen from the keratinocytes to the epidermal basement membrane, correcting the structure of the anchoring fibrils and maintaining the dermal-epidermal junction.
The incidence of TBDN does not exhibit a difference in sex or race/ethnicity. While some cases of TBDN seem to be sporadic, studies have shown that it can be inherited in an autosomal dominant or recessive pattern as well as in a compound heterozygous fashion, in association with different mutations in the type VII collagen gene COL7A1.
For more information, see OMIM.
Q81.2 – Epidermolysis bullosa dystrophica
254185007 – Epidermolysis bullosa dystrophica
Differential diagnoses of TBDN include:
- Group B streptococcal (GBS) sepsis
- Herpes simplex virus (HSV) – Look for grouped vesicles appearing shortly after birth on the infant's scalp, face, oral mucosa, or conjunctiva.
- Incontinentia pigmenti
- Bullous impetigo
- Erythema multiforme