Indian Journal of Radiology and Imaging Indian Journal of Radiology and Imaging

: 2001  |  Volume : 11  |  Issue : 3  |  Page : 151--152


SS Pawar, V Bhorge 
 Department of Radiodiagnosis and Imaging, B.J. Medical College and Sassoon General Hospital, Pune 411001, India

Correspondence Address:
S S Pawar
Department of Radiodiagnosis and Imaging, B.J. Medical College and Sassoon General Hospital, Pune 411001

How to cite this article:
Pawar S S, Bhorge V. Pyknodystosis.Indian J Radiol Imaging 2001;11:151-152

How to cite this URL:
Pawar S S, Bhorge V. Pyknodystosis. Indian J Radiol Imaging [serial online] 2001 [cited 2020 Sep 24 ];11:151-152
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Full Text


We wish to report a case of 'Pyknodysostosis'.

A nineteen-years-old girl was referred for a skeletal survey as she had a fractured tibia following trivial trauma.

Skeletal survey revealed the following radiographic features.

1) Skull showed evidence of brachycephaly, wide sutures and open fontanels. All bones showed increased bone density. The mandible was obtuse.

2) The limbs showed an overall increased bone density and pathological fractures.

3) Hands showed evidence of acro-osteolysis.

4) Pelvic bones, chest and spine did not show any abnormality other than increased bone density.

Physical examination revealed a short stature, a big forehead with frontal bossing and short stubby fingers. No other family members showed similar features. There was no history of consanguineous marriages.

The radiograph of the mandible was highly suggestive. Hence a diagnosis of pyknodysostosis was made.

Pyknodysostosis is a rare disease found in all races. It is inherited as an autosomal recessive disorder and may be found in the offspring of consanguineous marriages. Dwarfism is a characteristic feature of this disease [1].

Clinical features include frontal and occipital bossing, small face, receding chin, short broad hands and hypoplastic nails in a short patient [2]. Irregular dentition and respiratory problems may be seen in some [3].

Radiographic findings in the skull include failure of sutural fusion, open fontanels, Wormian bones, sclerosis of the skull base and brachycephaly. The skull tables and orbital rims are very dense. The facial bones are small and maxillae are hypoplastic. The mandible shows a feature distinguishing it from other conditions. It is hypoplastic and shows abnormal angulation [2]. Some authors have described this appearance as wide-angle [1] or no angle of the mandible. Mastoids are poorly developed [2].

The limbs reveal dense cortices. Medullary canals are not completely obliterated. The skeleton is susceptible to fractures [1],[2]. Modeling abnormalities if seen are mild [2].

In the thorax, clavicular hypoplasia may be present to a varying degree. The ribs show overall increase in bone density [1].

The spine may show spondylolisthesis and spool-shaped vertebral bodies [1]. Errors of segmentation may be evident [2]. Bones of the hands and feet are short and may show acro-osteolysis [1].

In our patient, the diagnosis was relatively straightforward because of the very typical appearance of the mandible. In some patients, the condition may be confused with cleido-cranial dysplasia (CCD) because of the hypoplasia of clavicles and facial bones. However, CCD is associated with a normal mandibular angle and normal or slightly reduced bone density. Obtuse angle of the mandible may also be found in acromegaly [1]. Hyperplastic sinuses and thickening of the skull vault seen in acromegaly are not a feature of pyknodysostosis.

Another condition with which pyknodysostosis is confused is osteopetrosis. This is because of the overall increase in bone density. However, osteopetrosis is associated with anemia, a bone in bone appearance, modeling abnormalities in long bones and a normal mandibular angle. The hands do not show acro-osteolysis. Spondylolisthesis may be seen in both conditions but was not seen in our patient. Dwarfism, a feature of pyknodysostosis is not seen in CCD or in osteopetrosis.


1Sutton D. Textbook of radiology and imaging Vol. I, 6th ed.; New York: Churchill Livingstone, 1998: 13-14.
2Resnick D. Bone and joint imaging. Philadelphia: W.B. Saunders, 1989: 1048-1049.
3Grainger RG, Allison DJ. Diagnostic radiology: a textbook of medical imaging. 3rd ed. New York: Churchill Livingstone. 1745-1771