Hyperostosis cranialis interna (HCIN) is a bone disorder characterized by endosteal hyperostosis and osteosclerosis of the calvaria and the skull base. The progressive bone overgrowth causes entrapment and dysfunction of cranial nerves I, II, V, VII, and VIII (Waterval et al., 2010).

A rare genetic disease characterized by sclerosing dysplasia affecting the diaphyseal and metaphyseal regions of the long bones, as well as the skull and metacarpals, in association with skin changes like those seen in ichthyosis vulgaris and premature ovarian failure with bilateral hypoplasia of the ovaries. Patients present in adulthood, primarily with swelling of the extremities and occasional mild pain in the legs.