Gracile Bone Dysplasia With Hydrops and Dysmorphism: Expanding the Phenotype and Literature Review

Abstract

Gracile bone dysplasia is a rare, inherited disorder characterized by slender, pencil-thin, and brittle bones. This lethal skeletal dysplasia, together with hydrops, facial dysmorphism, and absent germ cells, has only been reported once in the literature. We present a case of a preterm infant with gracile bones, cystic hygroma, and presence of ovarian germ cells. This report expands the phenotype of this syndrome. An African American preterm female infant was born to a 23-year-old G2P2 woman via emergency cesarean section for prolonged fetal heart rate deceleration. At 27 weeks, prenatal ultrasound showed multiple anomalies: polyhydramnios, cystic hygroma, hydrops, and bilateral club feet. At birth, the infant had generalized edema, scattered petechial hemorrhages, and irregular heartbeat, with no spontaneous respiration. Despite resuscitative measures, the infant died 1 hour after birth. Postmortem examination showed hydrops fetalis characterized by generalized edema of the face and upper back, with bilateral pleural effusion. Lung hypoplasia with unexpanded alveoli, extensive acinar formation, and abortive hyaline membranes were present. Normal germ cells were present in the ovaries. Histopathology of the neck, thymus, and pancreas showed an increase in lymphatic channels suggestive of defective lymphangiogenesis. The skeletal system showed multiple upper and lower extremity deformities consistent with gracile bone dysplasia. The long bones were extremely thin and fragile. Bilateral fractures of proximal humeri and bilateral talipes equinovarus were present and confirmed radiographically. The exact etiology of the gracile bone dysplasia is unknown. There have been reports of 2 siblings in 1 family afflicted, and an autosomal recessive pattern of inheritance has been postulated. Nonimmune cystic hygroma with abnormal lymphangiogenesis as seen in this case may suggest a lymphatic origin of this disease. Accurate diagnosis is imperative for prenatal genetic counseling and screening for occurrence in subsequent pregnancies.