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A condition, either congenital or acquired, in which the head is abnormally large; usually applied to an adult cranium with a capacity of over 1450 mL.
Synonym(s): leontiasis ossea, macrocephaly, macrocephalia, megacephalia, megalocephaly, megalocephalia, Virchow disease
[mega- + G. kephalē, head]
McCune-Albright syndromeAn autosomal dominant condition (OMIM:174800) due to altered regulation of cAMP, endocrinopathy (e.g., hyperthyroidism) and hypophosphatemia.
Precocious puberty, polyostotic (cystic fibrous dysplasia) spontaneous fractures at young age, café-au-lait spots on skin, ovarian cysts.
Cyclical 4–6-week fluctuations of plasma oestrogen; afflicted young girls have decreased gonadotropins, decreased response to LH-RH; increased testosterone, increased alkaline phosphatase.
Defects in GNAS, which encodes a G protein that modulates various membrane signalling cascasdes, cause McCune-Albright syndrome.
Aromatase inhibitor testolactone.
Enlargement and distortion of facial bones, giving one the appearance of a lion. It can occur as a complication of hyperparathyroidism, Paget's disease, uremia, and other conditions.
See also: leontiasis