Extramedullary hematopoiesis secondary to COVID-19: A first case report in a newborn

Introduction

Extramedullary hematopoiesis occurs naturally in fetuses and normally ceases before birth. In newborn babies, it happens secondarily to a bone marrow dysfunction. The most common causes of this condition are viral infections including cytomegalovirus and rubella, but also other congenital infections and neonatal anemias. The treatment of bone marrow dysfunction, which can occur spontaneously in the case of viral infections, solves the skin lesions.

Case presentation

We describe a 3260 g baby girl born by vaginal delivery at 39 weeks gestation. Her mother was a healthy 25-year-old and primiparous. Pregnancy was uneventful. Prenatal serologies and fetal ultrasounds were normal, levothyroxine-treated hypothyroidism was well controlled, and maternal blood group was B+ . On week 35 of pregnancy, mother was diagnosed with a mild form of COVID-19 infection confirmed by polymerase chain reaction (PCR) test. She presented premature rupture of membranes 18 hours prior to delivery, a positive urinary group B Streptococcus screen, and received prophylactic penicillin. On that day, a second COVID-19 PCR test was negative. The electronic fetal monitoring revealed fetus bradycardia during the second stage of delivery that did not require any intervention, but at birth the baby was healthy with Apgar scores at 8-9-9.

Dermatology consultation was requested on the first day of life for a congenital skin eruption. On physical examination, the baby presented about 30 violaceous petechial, 2-mm macules scattered on the lower half of the back bilaterally, as well as two larger purpuric papules. A skin biopsy confirmed the diagnosis of extramedullary hematopoiesis (Figure 1). Baby’s biological, hematological parameters, and hemoglobin electrophoresis were within normal limits except for elevated platelets (536 × 10⁹/L, normal 140–440 × 10⁹/L). The baby evolved well, and all macules and papules disappeared within 2 days.

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Figure 1.

High-power view revealing deep cutaneous extramedullary hematopoiesis, as identified within the yellow circles.

Infectious origins leading to extramedullary hematopoiesis showed no maternal exposure to toxoplasmosis, positive rubella IgG serology, and negative Cytomegalovirus PCR in the baby’s urine.

Discussion

Neonatal extramedullary hematopoiesis characterized by blueberry muffin baby may be secondary to congenital infections, hemolytic disease, twin-twin transfusion syndrome, neoplastic, autoimmune, or hematological disorders.^1–3 Most frequent are infections of the TORCH complex (toxoplasmosis, rubeola, cytomegalovirus, herpes).^4,5 This case was unique in that the mother had a confirmed case of COVID-19 (positive PCR test) shortly before giving birth, and this was the only risk factor explaining why COVID-19 was the likely cause of extramedullary hematopoiesis.

In conclusion, we suggest that COVID-19 infection should be considered in the differential diagnosis of blueberry muffin babies.