Discrepancy of prenatal findings in a monochorionic monoamniotic twin pregnancy – Infantile myofibromatosis

Introduction: Monoamniotic twin pregnancies are characterized by an increased rate of cord injuries due to entanglement and of prenatal malformations.

Case report: A monochorionic monoamniotic pregnancy was diagnosed in a 29 year old woman at 12 gestational weeks.

In the second trimester, an echodense tumor was seen on the right side of the head of one twin. Amniocentesis revealed a normal karyogram 46 XX. MRI showed a tumorlike configuration on the right side of the head without connection to the brain ventricles or brain tissue.

Within the third trimester, jejunal atresia of the same child was suspected by ultrasound. At 32 weeks, a primary caesarean section was performed. In the first twin a tumor on the right side of the fetal head was present and laparotomy revealed that the whole intestinum was involved and compressed by a tumor mass histologically classified as a form of infantile myofibromatosis with cerebral and visceral expansion. The twin died 12 days postnatally due to sepsis.The second twin developed uneventfully up to at least 6 months.

Discussion: Infantile myofibromatosis is a rare disease, but the most common proliferative mesenchymal disorder in the neonatal period and childhood. Usually the disorder is benign and solitary. The first twin suffered from the congenital multiple form with multicentric localisation and visceral expansion. This form has a bad prognosis with survival chances of 10–15%. When there is expansion towards the intestine the mortality rate increases towards 100%. The genetics and pathophysiology of this disorder is unknown. Whether the second child has an increased chance to develop a later form of the disease must remain open.