Acalvaria

What it is

A rare congenital malformation characterized by the absence of calvarial bones, dura mater and associated muscles while skull base, facial bones and brain structures are normal. Central nervous system is usually unaffected, however some neuropathological abnormalities such as holoprosencephaly, hydrocephalus, micropolygyria and gyration anomalies can be present. Prenatal diagnosis by ultrasonography is usually confirmed by magnetic resonance imaging as it can be confused with anencephaly or encephalocele.

Key facts

Prevalence

1-9 / 1 000 000 (at birth, Europe)

Age of onset

Antenatal, Neonatal

Inheritance

Not applicable

Classified as

Malformation syndrome

Prevalence figures describe populations, not individuals, and are often estimates from a single study. Where the figure is an incidence or a birth prevalence, it says so.

Signs and symptoms

These ranges are how often a sign appears across everyone diagnosed, not a prediction for one person — most people have some of these and not others. Orphanet also records findings that are specifically absent in this disease; those are in the data but not listed here.

ICD-10 codes

ICD-10 has no distinct code for most rare diseases, so many are filed under the nearest available one. A shared code identifies the group, not this disease — the ORPHAcode above is what identifies it.

Related health topics

Reached through the ICD-10 categories this disease is filed under, so these describe the broader group rather than this disease specifically.

Cross-references