Decreased calvarial ossification

What it means

Abnormal reduction in ossification of the calvaria (roof of the skull consisting of the frontal bone, parietal bones, temporal bones, and occipital bone).

A hypomineralised skull castes little or no acoustic shadow on prenatal ultrasound. This makes visualization of the intracranial anatomy clearer than normal. In conditions associated with profound hypomineralisation, the skull shape can be distorted by pressure from the ultrasound transducer later in pregnancy.

Rare diseases that can present with this2

The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.

Part of the broader category

Also called: Poorly ossified calvaria · Poorly ossified calvarium · Skull soft on palpation · Soft calvaria · Undermineralized calvarium