Placental electron microscopy and histochemistry in a case of sialic acid storage disorder

Mucolipidosis Type II Affecting 1 Fetus and Placental Disk of a Dichorionic-Diamnionic Twin Gestation: A Case Report and Review of the Literature

Mucolipidosis type II, also known as I-cell disease, is an autosomal recessive inborn error of metabolism, resulting from loss-of-function mutations in GNPTAB. Affected infants exhibit multiple physical anomalies and developmental delay, and death from disease follows in early childhood. Here we present an instructive case of mucolipidosis type II affecting 1 fetus and placental disk in a dichorionic-diamnionic twin pregnancy delivered at 36-wk gestation. The second twin and placental disk showed no abnormality. On microscopic examination, the affected placenta displayed marked vacuolization of the syncytiotrophoblast and Hofbauer cells, which was confirmed on ultrastructural examination. To our knowledge, this is the first description of placental findings in a twin pregnancy, wherein only 1 twin is affected by an inborn error of metabolism. This provides an opportunity to highlight the placental abnormalities seen in this group of diseases, and to emphasize the role of pathologic examination in early detection of otherwise unsuspected inborn errors of metabolism.

Ultrasound assessment in a case of sialic acid storage disease

A woman was referred to our unit at 25 weeks' gestation because of fetal ascites. Conventional and three-dimensional ultrasound examinations revealed coarse facies and micromelia which strongly suggested storage disease, despite the absence of an index familial case. Amniocentesis was performed and, in view of the poor prognosis, the pregnancy was terminated. Autopsy confirmed all the sonographic features and the cultured amniocytes confirmed the diagnosis of infantile sialic acid storage disease.

Identification of Gaucher cells in the chorionic villi associated with recurrent hydrops fetalis

Recurrent non-immune hydrops fetalis has rarely been reported. In order to detect the risk of recurrence in a subsequent pregnancy, one should carefully consider the possibility of an inborn error of metabolism. In such cases, placental examination may be useful in detecting such metabolic storage disorders in the fetus, which usually present as vacuolization of placental cells. We describe a rare case of recurrent hydrops that was detected by placental examination. Through light microscopy, electron microscope (EM) studies and beta-glucocerebrosidase activity the disease was identified as Gaucher's disease.

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 rectus abdominis, clubbing of the left foot, gingival hypertrophy, short first metatarsals, prominent scrotal raphe, right heart dilatation, and left ventricular dysfunction. Radiographs showed pulmonary hypoplasia and epiphyseal stippling. He died of respiratory failure at day 2. Autopsy demonstrated capillary hemangiomata, remote cerebral hemorrhages, and central nervous system periventricular leukomalacia, as well as severe cardio- and hepatosplenomegaly. Multiple single membrane-limited vacuoles consistent with enlarged lysosomes were present in virtually all cell types examined, with striking involvement of liver, myocardium, and placenta. Vacuolar contents were not identifiable by electron microscopy. Demonstration of elevated free sialic acid in urine, amniotic fluid, and cultured fibroblasts confirmed the diagnosis of ISSD. Characteristics of sialic acid storage diseases and their diagnosis are reviewed. ISSD should be considered in infants with empty cytoplasmic vacuoles in multiple tissue types.

Diagnosis of unsuspected fetal metabolic storage disease by routine placental examination

GM1 gangliosidosis (type 1) is a rare hereditary, autosomal recessive, lysosomal storage disease characterized by a marked deficiency of active acid beta-galactosidase resulting in accumulation of gangliosides and mucopolysaccharides in tissues. Disease status of newborns from affected kindreds may be diagnosed by placental examination. Typical findings include a characteristic vacuolar distension of the cytoplasm of syncytiotrophoblast and stromal Hofbauer cells. We report a case of unsuspected fetal storage disorder initially diagnosed by routine placental examination of a normal-appearing infant born to a previously unaffected family. Progressive, third-trimester oligohydramnios and fetal growth retardation had been documented by ultrasonography. Placental findings included vacuolization of syncytiotrophoblast, intermediate trophoblast, and stromal Hofbauer cells. Subsequent enzyme analysis confirmed the placental findings of storage disorder and diagnosed GM1 gangliosidosis.

Ultrastructure of the human placenta in metabolic storage disease

Eleven placentae and one fibroblast cell culture from pregnancies complicated by various inherited metabolic disorders, together with five chorionic villus biopsies from pregnancies at risk, were examined for ultrastructural evidence of accumulation of metabolites. Abnormal ultrastructural features were present as early as 10 weeks gestation. Myelin bodies were found in all placental cell types in a case of Niemann-Pick disorder and stromal cells showed marked vacuolation in Hurler's disease. Membranous arrays were occasionally identified in the lysosomes of stromal cells in a case of Sandhoff's disease, together with some myelin body formation in the trophoblast and endothelium. In Pompe's disease, intralysosomal accumulations of glycogen were present in all cell types except syncytiotrophoblast, while in sialic acid storage disorder all placental cells were affected except for the cytotrophoblast. Collagen fibre disorientation and excess associated proteoglycan was seen in a formalin-fixed placenta with Sanfilippo mucopolysaccharidosis, and syncytial vacuolation, caused possibly by delays in fixation, was evident in many specimens. The specimens were collected from different centres and the fixation procedure varied significantly. The most satisfactory results were obtained from chorionic villus sampling in vivo and from pregnancies terminated using aspiration followed by immediate fixation. The importance of liaison with clinicians is stressed in order to obtain optimal preservation of the tissue. This is particularly vital in immature specimens of placenta where abnormal storage product material may not have had time to accumulate.