Annular papular plaques in a newborn

Paediatric dermatology

Dr. Emmanuelle Bourrat

Saint-Louis Hospital

The clinical case
Now it's your turn!
Co-prescription and advice

Clinical case presentation

A 21-day-old female neonate presented to the pediatric emergency department with a rash that had been evolving for a week. She had a history of maternal-fetal streptococcal infection treated with amoxicillin and amikacin, and the mother had chronic hepatitis B, which justified early vaccination of the child.

The child was in good general condition and had no extracutaneous complaints. Her rash, which began on the face, progressively spread to all four limbs, including the soles. The lesions were annular, erythematous and highly infiltrated, with a depressed purplish center. A biopsy was performed the same day, and a standard workup and imaging (chest X-ray and abdominal ultrasound) were unremarkable.

Your turn

What is your diagnosis?

Select 1 answer(s) from the following choices:

Urticaria

Sweet's syndrome

Neonatal lupus

Wrong answer!

Good answer!

Selected diagnosis

The histological appearance of these annular papular plaques is that of a suspicious, predominantly histiocytic infiltrate, which should prompt consideration of a possible cutaneous localization of leukemia with a monoblastic component.

Histiocytoid Sweet's syndrome is also possible. The hematological work-up confirms a normal CBC and blood smear and the absence of lysis syndrome, but the myelogram shows a marrow rich in physiological precursors compatible with age, with the presence of a myeloid blast population between 4 and 5%.

The bone marrow karyotype was normal, the noncontributory phenotype not allowing identification of a clonal population.

The diagnosis is histiocytoid Sweet's syndrome or medullary and cutaneous myelodysplasia. The spontaneous evolution, under very close clinical and hematological surveillance, was rapidly favorable, with disappearance of the bone marrow blastosis and rapid regression of the skin lesions, a complete remission that was maintained at 18 months' follow-up.

Explanation of wrong answers

Urticaria is usually annular with a hemorrhagic component in young children, but its fixed nature is a sign of atypia and requires biopsy.
Neonatal lupus is lupus that is passively transmitted in utero by a mother who carries anti-SSA or anti-SSB antibodies. The most typical skin lesions are orbital erythema and annular, scaly, erythematous macules with little or no infiltration, with a bipolar distribution (head and buttocks) in a newborn. Diagnosis is based on the detection of lupus autoantibodies in the mother.

Message from the expert

Cutaneous myelodysplasia and histiocytoid Sweet’s syndrome are closely related manifestations that have so far been described mainly in adults.

Like all hematologic disorders, they occur not only in children but also in newborns.

References

^{Vignon-Pennamen MD, Battistella M.}^{From Histiocytoid Sweet Syndrome to Myelodysplasia Cutis: History and Perspectives.}^{Dermatol Clin. 2024 Apr;42(2):209-217}