Pyknodysostosis

Case contributed by Andrew Dixon
Diagnosis certain

Presentation

Short stature. All images presented in this case were obtained at age 9 years except for the CT of the skull which was performed at age 7 years.

Patient Data

Age: 9 years
x-ray

There is generalized osteosclerosis with narrowing of the medullary cavity. The fingers are short and stubby and there is partial agenesis/aplasia of terminal phalanges simulating acroosteolysis.  When compared to a reference standard there is a two-year delay in hand bone age.

There is an incompletely healed transverse fracture of the tibial shaft.  

mri

There is a triangular shape to the frontal cranium (trigonocephaly) due to relative early fusion of the metopic suture.  

ct

The cranial sutures, which should be nearly completely fused at this age remain widely open.  There is a triangular shape to the frontal cranium (trigonocephaly) due to relative early fusion of the metopic suture.  

Case Discussion

These imaging findings are consistent with pyknodysostosis.

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