Chromosome: 4p16.3
Gene: SH3BP2 (SHE-domain binding protein 2)
Mechanism: The mutation in SH3BP2 stimulates RANKL-induced activation of PLC-gamma, with activation of calcineurin and NFAT proteins, which in turn cause osteoclastogenesis (Lietman et al).
Inheritance: autosomal dominant
Clinical features:
(1) The patient presents with painless bilateral enlargement of the mandible and/or maxilla.
(2) It usually appears in early childhood and then spontaneously regresses after puberty.
(3) Affected bone shows multilocular cysts composed of a fibrous stroma and osteoclast-like giant cells forming granuloma-like lesions.
Complications in moderate and severe cases:
(1) dental loss or misalignment
(2) difficulty with speech
(3) difficulty breathing
(4) difficulty eating and swallowing
(5) visual impairment from displacement or compression of globe and/or optic nerve
Therapy may not be required in mild cases. More severe cases may be treated by:
(1) surgery to remove affected tissue with or without bone grafts
(2) administration of calcitonin (may be delivered intransally)
