Criteria for TBDN:
(1) presence of primary vesiculobullous skin lesions primarily on the extremities
(2) lesions are present at birth or develop in the newborn period following skin friction
(3) spontaneous cessation of new lesions during infancy (within a few months of birth)
(4) absence of dystrophic scarring
A skin biopsy shows subepidermal bulla with cytoplasmic granules (stellate bodies) in the epidermis.
Additional factors for the diagnosis:
(1) presence of a family history
(2) exclusion of alternative diagnoses
Electron microscopy shows:
(1) collagenolysis and damage to anchoring fibrils
(2) vacuolar dilatation of endoplasmic reticulum (ER) with stellate bodies of keratinocytes
(3) discharge of ER vacuoles into the dermis through a rupture in the basal lamina
