Platyspondylic lethal skeletal dysplasia
Fabrice Cuillier1, Mardamootoo D.
1, Dr Alessandri J.L.
2, Dr Scemama J.M.
3, Dr Chance P
.3
1 Service de Gynécologie, Hôpital F. Guyon, 97400 Saint-Denis, Réunion, France.
2 Service de Néonatologie, Hôpital F. Guyon, 97400 Saint-Denis, Réunion, France.
3 Cabinet de Radiologie, 97400 Saint-Paul, Réunion, France.
Definition:
Lethal chondrodysplasia (CDD) or platyspondylic (PLSD) are heterogeneous groups, with thanatophoric dysplasia (TD) and some variants, as PLSD type San Diego (PLSD-SD), Torrance (PLSD-T) and Luton (PLSD-L) (or platyspondylic nanism type San Diego, Torrance ou Luton).
Thanatophoric dysplasia is divided in 2 groups (TD1 and TD2), according to clinical, radiological and biochimical factors (in particular, Fibroblast Growth factors Receptors 3 (FGFR3) mutation). Thanatophoric dysplasia variants are different due to radiological and chondro-osseous criteria. Platyspondylic lethal skeletal dysplasia are severe disorders of bone growth. Patients with this illness have very short arms and legs, a small chest with short ribs, underdevelopped pelvic bones and unusually short fingers and toes, called brachydactyly. This disorder is also characterized by flattened spinal bones (platyspondyly) and abnormal curvature of the spine.
In this article, we describe a case of thanatophore dysplasia type 1.
Case report:
A 26-year-old patient was referred for a second opinion at 21 weeks. The couple was nonconsanguineous. Her husband was 58 years old. He has four healthy children.
At 13 weeks, the nuchal translucency was 1 mm. The triple test was not performed.
At 20 weeks, we found that the upper and lower limbs were very short, and other ultrasound findings were:
- Macrocrania (Figure 1, 2), normal facial profile (Figure 3, 4): The facial profile didn’t show frontal bossing. Achondroplasia and achondrogenesis were eliminated.
- Micromelia of upper and lower limbs without hexadactyly was confirmed on 2D and 3D ultrasound with bilateral curved femur.
- Clavicles were normal. Cleido-cranien chondrodysplasia was excluded.
- 3D thoracic sonography confirmed the presence of the scapula which appeared normal (Figure 20-21).
- Narrow thorax
- 3D sonography of the pelvis showed normal iliac bones without inferior spines (Figure 23-26).
- A platyspondy was suspected. There were 12 ribs.
Our diagnosis was thanatophoric dysplasia type I. Thanatophoric dysplasia type II was eliminated because clovercleaf was absent. Interruption of pregnancy was done. Postmortem examination confirmed platyspondylic chondrodysplasia, with high intervertebral space level on radiography (Figure N°12A, 12B). The autopsy was refused. Limbs were short and rhizomelic without wide metaphysis. The thorax was narrow, with broad short ribs (« en palette »).
The final diagnosis was lethal nanism platyspondylic, thanatophoric dysplasia type I.
Figure 1, 2 :
3D sagital sonography view of the face and 2D transverse view of the cranium (macrocrania) at 21 weeks.