The appearance of blueberry muffin spots in a newborn is most consistent with which process?

• A. Congenital thrombocytopenia
• B. Extramedullary hematopoiesis
• C. Transient abnormal myelopoiesis
• D. Hyperbilirubinemia

Answer: (A)

Blueberry muffin spots arise from extramedullary hematopoiesis in the skin. When hematopoiesis occurs outside the bone marrow, especially in the fetal period or in response to stress or disease, immature blood cells can seed the dermis and form blue-purple papules or nodules. This finding is classically seen in newborns with congenital infections (like CMV, rubella, toxoplasmosis, syphilis) or certain hematologic conditions.

In contrast, congenital thrombocytopenia would present with flat purpura or petechiae from bleeding due to low platelets, not raised blue-purple skin nodules. Hyperbilirubinemia causes jaundice, not skin lesions. Transient abnormal myelopoiesis can involve abnormal white cells and organomegaly but does not explain the characteristic blueberry muffin skin lesions.