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Infantile Pyknocytosis

An Uncommon Cause of Newborn Hemolytic Anemia

Castillo, Jayme BS*; Ness, Tara E. MD, MPH*,†; Mehta, Parth S. MD, MPH*,†

Journal of Pediatric Hematology/Oncology: March 29, 2019 - Volume Publish Ahead of Print - Issue - p
doi: 10.1097/MPH.0000000000001461
Clinical and Laboratory Observations: PDF Only

Infantile pyknocytosis is a rare cause of neonatal hemolytic anemia, which presents in the first few weeks of life. We report a classic case of infantile pyknocytosis that presented to our institution with rebound hyperbilirubinemia after receiving phototherapy. The infant was found to have a hemoglobin of 5.8 g/dL, requiring a total of 15 mL/kg of red blood cells (in 2 separate transfusions) before discharge. The diagnosis was ultimately made by a review of the peripheral blood smear. We review the literature and suggest pediatricians consider infantile pyknocytosis on their differential when hemolytic anemia presents in the newborn period.

*Baylor College of Medicine

Texas Children’s Hospital, Houston, TX

The authors declare no conflict of interest.

Reprints: Jayme Castillo, BS, Office of Student Affairs, Baylor College of Medicine, 1 Baylor Plaza, Houston, TX 77030 (e-mail:

Received November 4, 2018

Accepted February 1, 2019

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