Pyknodysostosis

Findings: The bones are diffusely sclerotic evidenced by loss of the cortical medullary differentiation.

Discussion: Pyknodysostosis a hereditary syndrome of dwarfism, osteopetrosis, and skeletal anomalies of the cranium, digits, and mandible.

The inheritance is autosomal recessive. It is estimated that 10% of patients have developmental delay and mild acromelic dwarfism.

On skeletal survey the nose is beaked and the jaw is hypoplastic with an obtuse mandibular angle. The hands demonstrate characteristic hypoplastic terminal phalanges. Even with an increase in bone density, these patients are at risk for multiple fractures.

The differential diagnosis for diffuse sclerotic bones includes:

M - metastases
M - mastocytosis
M - myelofibrosis
'
S - sickle cell anemia

P - Paget's
R - renal osteodystrophy
O - osteopoilikosis
O - osteopetrosis
F - fluorosis

Source: Jacobson HG. Dense bone--too much bone: radiological considerations and differential diagnosis. Part II. Skeletal Radiol. 1985;13(2):97-113.