Alder-Reilly Anomaly in the Cerebrospinal Fluid of a Child With Hurler Syndrome

: Hurler syndrome is an autosomal recessive mucopolysaccharidosis characterized by intralysosomal accumulation of glycosaminoglycan fragments, with cellular accumulation of distended lysosomes resulting in interference with normal cell function. One of the peripheral blood features of mucopolysaccharidoses is the presence of numerous, dark lilac granules within lymphocytes, monocytes, and neutrophils, also known at Alder-Reilly anomaly. Here we describe intracytoplasmic granules with haloes in mononuclear cells present in the cerebrospinal fluid of a 2-year-old boy with the diagnosis of Hurler syndrome, undergoing pretransplant evaluation for an unrelated donor cord blood stem cell transplant.