[Papulo-erythematous eruption of neonatal lupus]

Neonatal lupus is rare and cutaneous lesions are usually suggestive of the diagnosis. We describe the case an infant with atypical clinical and histological aspects.

A female newborn, 6 weeks of life, presented since 3 weeks a papulo-erythematous eruption involving the trunk and the 4 limbs. Cutaneous biopsy showed a dermal infiltrate of mononuclear cells, which corresponded morphologically to lymphocytes. But myelo-monocytic origin was proved by immunostaining. This result could be seen in hematodermia and macrophagic activation syndrome, but we had no clinical sign for these diagnosis. Later, she presented an erythema of the eyelids and erythematous papules of the face leading to suspicion of neonatal lupus. Questioning the mother revealed that she had Raynaud's syndrome since 1995. Antinuclear factors were positive in the patient and her mother, corresponding to antiSSA and antiSSB antibodies. She exhibited cytolytic hepatitis but no congenital heart block. Direct immunofluorescence was negative. The clinical evolution was good with complete clearing of the eruption at the age of 3 months. At 10 months, clinical and biological examinations were normal, with no arguments for haematological disease.

This observation is original because of the initial papulo-erythematous eruption which is rare in neonatal lupus. Diagnosis was confirmed when specific secondary cutaneous lesions appeared. The biopsy of the first eruption showed a myelo-monocytic infiltrate which has never been described in neonatal lupus. However cutaneous biopsies are rarely performed in neonatal lupus and immunostaining is lacking in the literature.