Diversity of neuromuscular pathology in lethal multiple pterygium syndrome

Lethal multiple pterygium syndrome (LMPS) is an uncommon fetal-onset disorder of unknown etiology. The pathogenesis of LMPS has been suggested to be earlyonset fetal akinesia, fragile collagen, or generalized edema. Information on the neuromuscular pathology of LMPS in the literature is generally scanty. We present the findings from a review of 14 fetuses with features of LMPS from the archives of the Hammersmith Hospital Perinatal Pathology Department. Autopsy reports, photographs, fetograms, and histological sections were examined, and additional special stains and immunostaining were performed on muscle sections. In five cases, there was evidence of autosomal recessive inheritance. One case was later shown to be due to glycogen storage disease type IV. The skeletal muscle bulk was reduced in all fetuses and the remaining muscle showed a range of histological appearances including vacuolar degeneration, dystrophy, a generalized or patchy myotubular appearance, and generalized hypotrophy. In one, the histological appearance was essentially normal. Two cases had abnormalities in the brain. Large motor neurons were present in the anterior spinal horns of all fetuses in whom the spinal cord could be examined. There was no evidence of cartilaginous joint fusion. We conclude that LMPS is the phenotype resulting from fetal akinesia commencing in the first or early second trimester. In the majority of cases, the precise underlying cause will not be identified, however, occasionally a metabolic or neurodevelopmental disorder or a specific primary myopathy may be demonstrated, providing adequate autopsy investigations are under-taken.