A 5-year-old boy was brought for evaluation of ongoing thrombocytopenia before undergoing adenotonsillectomy for obstructive sleep apnea. The child had been given a diagnosis of "growing pains" after frequent evaluation for leg pain over the past 2 years. He also exhibited easy bruising and frequent epistaxis without other avenues of blood loss. There was no family history of a blood disorder, except for his maternal grandfather who had easy bruising of undetermined cause.
The child was born to Ashkenazi Jewish parents after a pregnancy complicated by 3 maternal transfusions for iron deficiency anemia that resolved postpartum; the delivery and neonatal stay were unremarkable.
As an infant, he had extensive eczema, abdominal pain, diarrhea, and poor weight gain attributed to allergic enteropathy; these conditions responded well to an elemental formula. As a toddler, he had 9 hospitalizations for asthma that became less frequent after age 2 years through standard controller therapy. His development was appropriate for age, and he had no history of regression.
Physical examination revealed a well-nourished boy with weight at the 50th percentile and height at the 16th percentile; vital signs were normal. Significant findings included coarse facial appearance; prominent forehead; multiple ecchymoses on the trunk and extremities (none on the mucous membranes); a firm, nontender liver about 5 cm below the costal margin; and a spleen 8 cm below the costal margin. There was no audible bruit over the liver, spleen, or abdomen; no pallor, jaundice, hemangioma, lymphadenopathy, rash, or bony tenderness; and no abnormalities of the genitalia or fundi.
During the 2 years of monitoring for asthma and leg pain, the white blood cell count ranged from 2.4 to 7.3 x 109/µL and the platelet count from 108 to 160 x 109/µL; the differential and peripheral smear were normal. Red cell indices showed a mean corpuscular volume of 81.4 to 87 fL, mean corpuscular hemoglobin concentration of 33.1 to 35.8 g/dL, and red cell distribution width of 12.7% to 14.8%, with a reticulocyte count of 0.7%. A coagulation profile, iron studies, electrolyte levels, liver function test results, lipid profile, sweat chloride test results, C-reactive protein level, erythrocyte sedimentation rate (ESR), and immunoglobulin levels were all normal. Serological titers of Epstein-Barr virus (EBV), HIV, Cytomegalovirus (CMV), hepatitis C virus (HCV), and mycoplasma were not elevated. CT scans of the chest and abdomen were normal, and chest radiographs revealed occasional infiltrates associated with asthma exacerbations.