Mandibular periosteal new bone formation (the "mandibular mantle") is described in very low birth weight infants with other signs of severe metabolic bone disease. In infants with onset of dyspnoea and apnoea, between two and three months of age, this mandibular change suggests that the lung disorder is of skeletal, rather than pulmonary origin and aids in differentiation therefore, from the Mikity-Wilson Syndrome (pulmonary dystmaturity).