Generalized pustular psoriasis of pregnancy (impetigo herpetiformis)

A 17-year-old woman had a sudden eruption of pustules in her intertriginous areas as well as of erythematosquamous plaques on the scalp, elbows, palms and soles in the third trimester of her first pregnancy. Histopathological evaluation of a biopsy revealed typical changes of pustular psoriasis with parakeratosis and abscesses of neutrophils (Kogoj's spongiform pustules). The diagnosis of pustular psoriasis was established by the typical clinical and histopathological findings. Laboratory parameters showed a highly elevated blood sedimentation rate, hypoferric anemia and decreased albumin levels. Serum concentrations of parathormone and its metabolites were normal. After systemic treatment with glucocorticosteroids and antibiotics, the lesions improved but did not clear. After delivery of a healthy boy, therapy was switched to retinoid photochemotherapy with isotretinoin and PUVA that resulted in rapid and complete clearing of the eruption. The coincidence of plaque-type psoriasis and a pustular eruption as described previously in impetigo herpetiformis supports the view that this dermatosis of pregnancy is a variant of generalized pustular psoriasis.