The clues here are the very early onset, the absence of fever and mucosal disease, and the maternal autoimmune history. Together they describe a baby who has received antibodies across the placenta rather than acquired an infection or inherited a fragile skin. In neonatal pemphigus, maternal IgG directed against desmoglein crosses to the fetus and drives intraepidermal acantholysis, producing flaccid blisters and erosions on the face and trunk. Because the antibodies are passively acquired, the condition is transient and resolves as the infant clears maternal immunoglobulin over a few weeks, and the child remains systemically well.
The distractors fail specific tests. Staphylococcal scalded skin syndrome is toxin-mediated and presents with a febrile, irritable infant with periorificial crusting and widespread tender peeling, unconnected to maternal disease. Bullous pemphigoid is a disorder of the elderly and is vanishingly rare in newborns. Epidermolysis bullosa is a genetic, trauma-induced blistering disease, not an antibody-driven one. The picture therefore fits passively transferred pemphigus.
\[\boxed{\text{Neonatal pemphigus (transplacental maternal antibodies)}}\]