Marble bone disease/ Albers Schonberg disease/ Chalk BonesOsteopetrosis features are an increase in bone density, diffuse and focal sclerosis, modeling defects at metaphysis, pathological fractures, osteomyelitis, and dental abnormalities are features.
Complications:
- Decrease development of bone marrow– Fatal
- Bony encroachment on cranial foramina–Deafness, optic atrophy, facial paralysis
Etiology of Osteopetrosis
Unknown
Severe forms are Autosomal Recessive (AR)
Mild forms are Autosomal Dominant (AD)
Pathology of Osteopetrosis
- Failure of osteoclast function or development of continued deposition of new bone on unresolved calcified cartilages or primary spongiosa
- Starts before or at birth ( till growth stops)
- Medullary cavity: Obliterated
Grossly: brittle of chalk/ as hard as marble
Microscopic examinations: Increase and disorganised trabeculae/ Rare haversian canal
Skull: diploe are fused as one
Vertebrae: a transverse band of dense bone at other extremities
Clinical Features of Osteopetrosis
AR Variant:
Life-threatening, predisposed to fractures and infections
Fractures are transverse and sharply abrupt
Impairment of longitudinal growth: Short stature
Skull Changes: Choanal Stenosis and hydrocephalus
Macrocephaly, frontal boosting
Expanded bone marrows neural foramina: Blindness, Hearing loss, Facial palsy
Tooth eruption defect and dental caries
Hypocalcemia: tetanic seizures + hyperparathyroidism
Bone marrow suppression: Pancytopenia with intramedullary hematopoiesis (Liver/ Spleen)
AD Variant:
Confined to skeleton
Includes fractures, scoliosis, OA, and infections
Less severe forms
Other Variants:
OLEDAID: X-linked osteopetrosis + Lymphedema + Anhidrotic ectodermal dysplasia and Immunodefiency
ARO + Renal tubular acidosis
Neuropathic
Lab Investigations
S. calcium, PO4, and Ph are NORMAL
Tartrate resistant acid phosphatase (TRAP): Increased
Creatinine kinase BB iso-enzyme: Increased
Radiological Investigations
Uniformly dense bone (including epiphysis): Devoid of structures
Less dense bones: Interspaced
Clubbed metaphysics: Chiefly affected, enlargement ends abruptly at the junction of the diaphysis
Epiphysis: Central focus of dense or normal bone
Ilium: Often shows alternating dense and clear curved bands parallel with crest
(Bone with in Bone )
The density of the skull: Greatest at the base
Pituitary fossa: Small and thick clubbed posterior process close in on the fossa
Air sinus: Absent
Each vertebra displays a dense band at either end and a clear band between:-
Sandwich vertebrae or Ruggery Jersey Spine
Treatment Options regarding Osteopetrosis
If the family decides to continue with an affected pregnancy: Hematopoietic Stem Cell (HSCT) before the age of 3 months for a severe form
Routine dental and ophthalmic surveillance and maintenance of oral hygiene form an integral part
Fractures are difficult to treat: Brittle of bone
Secondary complications: Delayed union/ Non union/ Osteomyelitis
Prognosis
Severe form: Decrease life expectancy
Untreated: 1st decade: Bone marrow suppression
Adult form: Normal life expectancy
