Excess of neuromuscular spindles in a fetus with Costello syndrome: a clinicopathological report.

The neuromuscular spindle (NMS) is a proprioceptive myofibrillar component of skeletal muscles that is necessary to maintain normal muscle tone and coordination. Recently, an excess of NMS has been reported as a congenital neuromuscular syndrome with a Noonan phenotype, now linked to Costello syndrome (CS). The vast majority of patients with CS have a de novo heterozygous mutation in the HRAS gene involved in the Ras/mitogen-activated protein kinase (MAPK) pathway. CS has many features in common with Noonan and cardiofaciocutaneous syndromes, also linked to activating mutations (but in other genes) of the Ras/MAPK pathway. This makes the orientation of molecular screening difficult. The observation of excess NMS in a 26-weeks'-gestation stillborn prompted us to screen the HRAS gene for mutation. The identification of a HRAS mutation made it possible to establish a diagnosis of CS. We conclude that the excess of NMS is the most reliable sign for the diagnosis of CS. Our findings also show the instrumental role of histological study of the skeletal muscles in the context of polyhydramnios and fetal hydrops.

Vaginal delivery using cranioclasia following prenatal diagnosis of a giant fetal intracranial teratoma.

Intracranial teratoma, although a rare disease, is nonetheless the most common of the congenital tumors of the central nervous system in the neonatal period. It can be diagnosed antenatally by ultrasound. The prognosis for fetal forms of teratoma is very grim. We report here the case of an immature teratoma identified at 26 weeks' gestation and discuss its obstetric consequences, in particular, the technical procedures for a medically-indicated termination of pregnancy in view of the massive increase in head circumference associated with this tumor.