Transient bullous dermolysis of the newborn
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 7 collagen, the key structural protein in anchoring fibrils. Immunofluorescence reveals a granular pattern for type 7 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 7 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 7 collagen gene COL7A1.
Q81.2 – Epidermolysis bullosa dystrophica
254185007 – Epidermolysis bullosa dystrophica
Differential Diagnosis & Pitfalls
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