hyperostosis

Hyperostosis refers to excessive bone growth or thickening and can be localized to a single area or involve multiple skeletal regions. It results from irregular bone formation and remodeling and may be asymptomatic or cause symptoms through compression, stiffness, or functional impairment. Causes are multifactorial and can include age-related changes, metabolic factors, and genetic predisposition. Several distinct patterns are recognized clinically and radiographically.

Hyperostosis frontalis interna is a pattern in which the inner table of the frontal bone becomes thickened, often detected incidentally on skull imaging. It is more common in women and older adults and is usually benign. In some cases it associates with Morgagni-Stewart-Morel syndrome, characterized by obesity and endocrinologic abnormalities, though the clinical significance varies.

Diffuse idiopathic skeletal hyperostosis (DISH) involves extensive ossification of the anterior longitudinal ligament along the spine, typically in middle-aged or older individuals. Patients may experience gradual spinal stiffness and reduced range of motion; cervical involvement can lead to dysphagia or airway symptoms. Radiographic features include flowing anterior ossifications over at least four contiguous vertebral levels with relatively preserved intervertebral disc space and without inflammatory changes in the sacroiliac joints.

Other forms of hyperostosis may arise from degenerative osteophyte formation, traumatic healing, or rare genetic disorders such as craniometaphyseal dysplasia. The differential diagnosis includes ossified posterior longitudinal ligament and various osteoblastic or skeletal dysplasia conditions.

Diagnosis relies on imaging, with X-ray, CT, or MRI detailing bone proliferation patterns. Management is individualized: asymptomatic cases require no treatment; symptomatic cases use physical therapy and analgesia, and surgical intervention may be considered for nerve or organ compression or severe functional limitation, alongside management of underlying metabolic conditions in disorders like DISH.