11/11/2025
FETAL ANOMALY-THANOTOPHORIC DYSPLASIA
Thanatophoric dysplasia is a severe skeletal disorder characterized by a disproportionately small ribcage, extremely short limbs and folds of extra skin on the arms and legs.
prenatal ultrasound examination
First trimester
Shortening of the long bones, possibly visible as early as 12 to 14 weeks' gestation
Increased nuchal translucency
Second/third trimester
Growth deficiency with limb length below fifth centile recognizable by 20 weeks' gestation
Well-ossified spine and skull
Platyspondyly
Ventriculomegaly
Narrow chest cavity with short ribs
Polyhydramnios
Bowed femurs (TD type 1)
Brain anomalies
Cloverleaf skull. Craniosynostosis involving coronal, lambdoid, and sagittal sutures, resulting in a trilobed skull shape
Relative macrocephaly
Postnatal physical examination
Relative macrocephaly
Cloverleaf skull
Large anterior fontanelle
Frontal bossing, flat facies with a depressed nasal bridge, ocular proptosis
Marked shortening of the limbs (micromelia)
Redundant skin folds
Narrow bell-shaped thorax with short ribs and protuberant abdomen
Relatively normal trunk length
Brachydactyly with trident hand
Bowed femurs
Generalized hypotonia
Radiographs / other imaging studies
Rhizomelic shortening of the long bones
Irregular metaphyses of the long bones
Platyspondyly
Small foramen magnum with brain stem compression
Bowed femurs
Cloverleaf skull
CNS abnormalities including temporal lobe malformations, hydrocephalus, brain stem hypoplasia, neuronal migration abnormalities
Other rarely reported findings that are not part of the core phenotype include cardiac defects, renal abnormalities, and abnormalities of lymphatic development
