By Gary M. White, MD
Impetigo herpetiformis (IH) has been called pustular psoriasis of pregnancy because of its resemblance clinically and histologically to pustular psoriasis (of von Zumbusch). Indeed, some argue that this disease is pustular psoriasis that is triggered by the hormonal alterations of pregnancy. On the other hand, others argue that it represents a separate disease as many patients do not have a personal or family history of psoriasis. The affected patient, by definition, is a pregnant woman. Onset is usually in the third trimester although onset in the first trimester has been reported as well as one day postpartum [Dermatology 1999;199;400].
The patient experiences the onset of innumerable superficial pustules studded on the periphery of erythematous plaques. Lesions enlarge through peripheral extension. Nearly the entire cutaneous surface may become involved as well as the oral and esophageal mucosa. Fever, nausea and diarrhea may accompany the skin changes. The pustules are initially sterile but may become secondarily infected. They may rupture leading to limited or widespread erosions. Onset is typically in the third trimester and it may recur with subsequent pregnancies. Histologic examination shows intraepidermal pustule formation with a neutrophilic infiltrate.
Hypocalcemia has been reported to accompany IH and may be a precipitating factor. Tetany, delirium and convulsions may occur. Stillbirths, placental insufficiency and perinatal death are associated fetal complications. A flare of this disease precipitated by oral contraceptives has been reported. One patient had a Staphylococcus aureus lymphadenitis that seemed to precipitate the condition.
The pustules should be cultured to rule out other diseases or secondary infection. See differential for pustules.
The fetal status, maternal serum calcium levels and fluid status should be closely followed. Oral calcium, vitamin D3 and fluid replacement may be needed. A systemic corticosteroid (e.g. prednisone 1 mg/kg/d) is usually begun although UVB phototherapy is an alternative. In severe cases, therapeutic abortion, induction of labor and delivery or C section has been necessary.
Cyclosporin has been used successfully [AD 2002;138;128]. It may be given alone, or in combination with low dose steroids.
The disease usually remits after delivery but may recur in subsequent pregnancies. Maternal mortality is rare, but infant mortality may occur.
Indian J Dermatol 2010;55:181-4
Indian J Dermatol Venereol Leprol 2006;72:458-9
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