The commonest source of naturally acquired microchimerism, i.e. small numbers of foreign cells within the organism, is two-way mother-fetus transplacental trafficking during pregnancy. Here, the first report on coexistence of pregnancy-associated pemphigoid gestationis (PG) and progressive facial hemiatrophy, a form of “en coup de sabre” morphea, is presented. HE histopathology (eosinophil-rich subepidermal infiltration, inverted teardrop sign), direct immunofluorescence (linear IgG1, but not IgG4, deposits along the dermal-epidermal junction) and ELISA (elevated levels of serum and blister fluid IgG autoantibodies to BP180) corroborated the PG diagnosis. Microchimerism as a speculative shared background of those two rare autoimmune diseases is disputable.