Congenital infantile myofibroma causing intrauterine death in a twin.

While infantile myofibromatosis is the most common mesenchymal tumour of infancy, only around 300 cases have been reported. The authors report a 33-year-old para 1 with an uncomplicated, dichorionic diamniotic twin pregnancy who was diagnosed with an intrauterine death of one twin at 36+5 weeks gestation. At caesarean section, a macerated male stillborn weighing 2.72 kg was delivered. Postmortem examination revealed a pedunculated lesion attached to the left shoulder and underlying muscle consistent with a congenital myofibroma. The cause of death was postulated to be haemorrhage from the tumour surface causing fetal anaemia.