The snowflake sign. A sonographic marker for prenatal detection of fetal skin denudation.

Abstract

Fetal skin denudation is probably a rare phenomenon because the occurrence of bullae in the blister· formation skin disorders is a postnatal event. It has been suggested that the large skin defects observed in aplasia cutis congenita (ACC) might be the result of in utero peeling of skin secondary to fetal movements. 1 Moreover, the finding of high levels of alpha-fetoprotein in amniotic fluid with epidermolysis bullosa (EB) further suggests the occurrence of in utero blistering and denudation of skin. 2 We report two cases with blister-formation skin disorders, namely ACC and bullous ichthyosiform erythroderma (epidermolytic hyperkeratosis), where a distinctive sonographic sign representing in utero skin denudation was observed. The association of high maternal serum alpha-fetoprotein and this sonographic sign should raise the possibility of skin denudation disorders, especially when a previous positive family history is present. CASE REPORTCase 1 A 20-year-old Bedouin woman gravida 3, para 2, was refened for an ultrasound scan because of raised maternal serum alpha-fetoprotein. Two previous gestations had ended in the delivery of infants suffering from ACC. A single fetus was observed at 19 weeks' gestation as dated by the biparietal diameter, head circumference, abdominal circumference, and femur length. No fetal or placental abnormalities were detected. However, multiple small echogenic particles were observed floating in the amniotic cavity. These particles were detected whenever the fetus moved or when pressure was applied on the maternal abdomen during the scan. These particles resembled snowflakes (Fig. 1). The diagnosis of a third case of ACC was suggested, but the parents refused pregnancy termination. The snowflake sign was observed at further scans performed at 24, 26, and 28 weeks of gestation. The infant was born prematurely at 28 weeks of gestation, weighing 1,090 g. Skin was absent from the toes to the middle of the thighs with sparing of only the tips of the toes on the left foot (Figs. 2 and 3). Absence of skin was also noted on the dorsum of the left hand and wrist and from the right and left sides of the anterior upper neck. The infant died at 36 hours from severe respiratory distress. A cytogenetic study showed a normal female chromosome constitution (46,XX). Histologic examination of skin at the margin of denuded areas showed loss of epidermis with condensation of dermal collagen and inflammatory cellular infiltrate.Case 2 A 27 -year-old woman, gravida 2, para 1, was referred for sonography at 21 weeks' gestation because of discrepancy between size and dates. Her past medical history was uneventful, and one previous pregnancy had ended in the delivery of a normal infant. A single vertex-presenting fetus was ReceivedNovemberl3,1989, fromthe•ultrasoundUnit,Divisionof observed on ultrasound. No gross malformations were deObstetrics and Gynecology and fGenetics Unit, Soroka University tected, and fetal biometry corresponded to the dates. Again, as Hospital, Faculty of Health Sciences, Ben-Gurion...

Prenatal diagnosis of pyloric atresia-junctional epidermolysis bullosa syndrome in a fetus not known to be at risk

“…It may be necessary to have a signi®cant part of the skin affected in order to see this elevation, especially at the beginning of the pregnancy (Nesin et al, 1994;Achiron et al, 1992;Bick et al, 1987;Meizner and Carmi, 1990;Dolan et al, 1993). Moreover, pregnancies complicated by upper gastrointestinal atresias alone may have positive acetylcholinesterase (Holzgreve and Golbus, 1983).…”

“…Echogenic particles were at ®rst thought to be due to the presence of blood after amniocentesis, and later to sloughing of the skin:`snow¯ake' sign (Meizner and Carmi, 1990).…”

Does Amniotic Fluid Alpha-Fetoprotein Have Diagnostic or Prognostic Value at the Time of Second Midtrimester Genetic Amniocentesis?

“…There are few possibilities to diagnose the disease, also if ultrasonographic signs have been described. Meizner and Carmi [12] reported on a so-called snowflake sign probably related to skin denudation, and Achiron et al [13] reported deformities of the ear. This finding was not identified by Meizner and Carmi [12].…”

“…Meizner and Carmi [12] reported on a so-called snowflake sign probably related to skin denudation, and Achiron et al [13] reported deformities of the ear. This finding was not identified by Meizner and Carmi [12]. Therefore it is theoretically possible to suspect ACC using ultrasonography, but the most sensible indicator seems to be elevated AF AFP and the diagnosis can be only confirmed by skin biopsy as suggested by Rodeck et al [22].…”

“…However, in 1992 Platt et al [9], on the basis of their experience stated that ultrasonography is inadequate for the detection of all cases of spina bifida. There are other fetal pathological conditions in which AFP levels are elevated such as congenital nephrosis [10,11], aplasia cutis congenita (ACC) and epidermolysis bullosa, conditions in which US examinations do not play any significant role, but if possible US markers have been indicated in the case of aplasia cutis [12,13]. Moreover, abnormal AFP levels (high or low) have been found in association with fetal chromosomal anomalies [14,15].…”