Urticarial exanthema due to hepatitis B in a pregnant woman, mimicking a polymorphic eruption of pregnancy.

Hepatitis B virus (HBV) infection in pregnant women is very rare in western countries, thus, cutaneous manifestation of HBV infection may be confused with a dermatosis specific of pregnancy. We report a 39-year-old woman who presented in her 20th week of pregnancy with a pruritic rash, which consisted of generalized erythematous plaques, some of them with a purple centre. Serology testing showed acute HBV infection, and a biopsy revealed a superficial and interstitial perivascular inflammatory infiltrate of lymphocytes and eosinophils. A diagnosis of exanthema due to acute hepatitis B infection was established. The patient delivered a clinically healthy boy, who was given the first dose of the HBV vaccine and intravenous specific immunoglobulin, followed by the second dose 2 months later, and did not get infected with HBV. To our knowledge, this is the first case describing HBV exanthema in a pregnant woman, which led to early action for the newborn, avoiding vertical transmission and its high prevalence of cirrhosis and hepatocellular carcinoma.