Teaching Case

A thirteen-year-old girl presented in clinic with short stature failure to thrive and bowing of both legs. X-rays of the skull revealed widely open sutures and fontenalle, small facial bones with absent sinuses and an obtuse mandibular angle. The bones showed a uniformly increased density, and the medullary canal though distorted was still visible in all long bones.

A thirteen-year-old girl presented in clinic with short stature failure to thrive and bowing of both legs. There was no history of any injury in the recent past and no significant family history. A full skeletal survey was done. X-rays of the skull revealed widely open sutures and fontenalle, small facial bones with absent sinuses and an obtuse mandibular angle. The outer third of clavicle was absent bilaterally. There was loss of terminal tufts of the phalanges of the hand, and in some fingers the entire terminal phalanx was absent. Both tibias were bowed with old fracture lines still visible. The bones showed a uniformly increased density, and the medullary canal though distorted was still visible in all long bones.

Pycnodysostosis is considered to be an autosomal recessive disease with an incidence of under one per million. The usual presentation is dwarfism and recurrent fractures following trivial trauma. The patient may suffer a fracture at any age. They are more common in the lower limb and can result in deformities though they heal in the usual time period. The fracture lines may remain visible for a long time after it has healed. Mental retardation has been seen in a few patients though no definite association has been identified. They are usually short-limbed dwarfs, with a relatively large head, open anterior fontanellae and frontal and parietal bossing. There is persistence of deciduous teeth and can give the appearance of a double row of teeth. Dental carries is a frequent associated finding. Eyes may be normal or more often have some degree of proptosis. Clavicles are present with partial aplasia of the acromial ends, though in some cases it may be completely absent. Varying degree of khyphosis, scoliosis or a combination of the two may be present. The hands and feet have short terminal phalanges and abnormalities of the distal radio ulnar joint have been reported. Lab investigations when done, have been normal. Criteria for diagnosis are increased bone density of the entire skeleton without complete obliteration of the medullary canal and characteristic changes in the skull hand and long bones.