Understanding pregnancy dermatoses

July 1, 2007

Various gestational dermatoses can be difficult to diagnose, as many times itch is the patient's only presenting symptom. Adding to the complication, many diseases overlap and nomenclature can be confusing.

Key Points

London - Pregnant women frequently present to dermatologists with a somewhat unclear dermatosis and a single symptom: itch.

As this symptom alone is not indicative of any particular condition, physicians sometimes may find themselves at a loss in making a definitive diagnosis.

"At least 18 percent of women develop itching during pregnancy; however, oftentimes itching in itself is not diagnostically helpful. It is still necessary to fully evaluate and examine pregnant women to exclude the possibility of a co-existing dermatosis, a miscellaneous dermatosis arising in pregnancy or infestations such as scabies," says Martin M. Black, M.D., F.R.C.P., F.R.C.Path., emeritus professor of dermatologic immunopathology, St. John's Institute of Dermatology, Guy's, King's and St. Thomas' School of Medicine, St. Thomas Hospital.

Obstetric cholestasis

Itching and excoriations without primary lesions are the hallmark of obstetric cholestasis.

Cholestasis typically presents in the last trimester and may coincide with a urinary tract infection. Dr. Black says the diagnosis can be confirmed by verifying increased serum bile acids (cholic acid, deoxycholic acid and chenodeoxycholic acid).

"The condition should be handled by an obstetrician, as there is an undefined tendency to premature labor, fetal distress and even death - possibly as high as 13 percent," Dr. Black tells Dermatology Times.

Treatments for this condition include rest and a low-fat diet, UVB phototherapy and oral ursodeoxycholic acid (UDCA) dosed at 15 mg/kg/day.

Pemphigoid gestationis (PG)

Though a rare specific dermatosis of pregnancy, PG can be dramatic, with an explosive onset of pruritic tense blisters, and is even sometimes classified as a medical emergency.

It usually presents in late pregnancy, with a sudden onset of pruritic urticarial and vesicular lesions.

"The peri-umbilical area is a common localization, but annular urticated lesions may soon radiate outwards to other areas before tense blisters occur. In severe cases, PG can closely resemble bullous pemphigoid," Dr. Black says.

Immunofluorescence is essential for diagnosis, as a DIF demonstrates bright linear BMZ staining with C3 and IgG +/- in perilesional skin and circulating complement-fixing antibodies (IgG) in all active cases.

Dr. Black says the mainstay of therapy of PG is systemic corticosteroids, in which a dose of prednisolone dosed at 0.5 mg/kg usually suffices for most cases. He says cyclosporine, IVIG or possibly plasma exchange can also be effective as adjuvant therapies.

Polymorphic eruption of pregnancy

Polymorphic eruption of pregnancy (PEP or PUPPP) is a common dermatosis in pregnant women, affecting approximately 1 in 160 pregnant women.

It can occur in the late second trimester, third trimester and post-partum period, and is characterized by an intensely pruritic erythematous rash starting on the lower abdomen within the striae distensae, and spreading to the trunk and limbs, with rare involvement of the face, palms and soles of feet.

Dr. Black says the symptoms will usually resolve approximately four weeks following the disease onset. Therapy consists of emollients and moderately potent topical corticosteroids. More severe cases can be safely treated with a tapering course of oral prednisolone.

"Polymorphic eruption of pregnancy occurs predominantly in primigravidae, but important risk factors include excessive maternal weight gain and multiple pregnancies. Of all the specific dermatoses of pregnancy, PEP is the only condition to be statistically associated with multiple gestations. This suggests that abdominal distension is an important etiologic factor, perhaps by causing inflammation in the striae distensae," Dr. Black says.

Prurigo of pregnancy

Dr. Black says that prurigo of pregnancy is not an uncommon dermatosis and can affect one in 300 pregnancies.