INFANTILE SIALIC-ACID STORAGE DISEASE - A RARE CAUSE OF CYTOPLASMIC VACUOLATION IN PEDIATRIC-PATIENTS

We report a case of infantile sialic acid storage disease (ISSD) in a black infant presenting in utero with nonimmune hydrops, ascites, and anemia requiring intrauterine transfusion. Upon birth, the patient had prominent edema, large anterior fontanelle, partial absence of the re ctus abdominis, clubbing of the left foot, gingival hypertrophy, short first metatarsals, prominent scrotal raphe, right heart dilatation an d left ventricular dysfunction. Radiographs showed pulmonary hypoplasi a and epiphyseal stippling Ne died of respiratory failure at day 2. Au topsy demonstrated capillary hemangiomata, remote cerebral hemorrhages , and central nervous system periventricular leukomalacia, as well as severe cardio- and hepatosplenomegaly. Multiple single membrane-limite d vacuoles consistent with enlarged lysosomes were present in virtuall y all cell types examined, with striking involvement of liver, myocard ium, and placenta. Vacuolar contents were not identifiable by electron microscopy. Demonstration of elevated free sialic acid in urine, amni otic fluid, and cultured fibroblasts confirmed the diagnosis of ISSD. Characteristics of sialic acid storage diseases and their diagnosis ar e reviewed. ISSD should be considered in infants with empty cytoplasmi c vacuoles in multiple tissue types.