Leontiasis Ossea
Definition
- Descriptive term for lion-like facial appearance caused by diffuse craniofacial bone overgrowth
- Not a diagnosis, but a phenotypic manifestation of various bone disorders
Etymology
- Leō (Latin): lion
- -iasis: condition
- Ossea: bony
- → "Lion-like bone condition"
Radiologic Features
- Marked bony expansion of:
- Frontal bone
- Maxilla
- Mandible
- Zygomatic arches
- May cause:
- Facial deformity
- Proptosis
- Nasal obstruction
- Dental malocclusion
Common Causes
| Condition | Notes |
|---|---|
| Fibrous dysplasia | Most common cause; esp. in polyostotic form or McCune-Albright |
| Paget disease | Skull base involvement; older adults |
| Hyperparathyroidism | Rare; brown tumors or generalized resorption with overgrowth |
| Cherubism | Pediatric; bilateral jaw swelling, autosomal dominant |
| Acromegaly | Coarsening of facial bones; not true leontiasis but may mimic |
Clinical Relevance
- May result in:
- Visual loss (optic canal narrowing)
- Sinus obstruction
- Hearing impairment
- Often requires multidisciplinary evaluation: radiology, ENT, neurosurgery, endocrinology
Exam Tips
- “Lion-like facies + ground-glass craniofacial bones” → think polyostotic fibrous dysplasia
- “Older adult + skull thickening + hearing loss” → think Paget’s disease
- Link to GNAS mutation in McCune-Albright if endocrine signs present
