Inherited bone dysplasia affecting the enchondral
growth of long bones, which results in failure of modeling and causes
increased circumference of the ends of the shafts.
Pyle Metaphyseal Dysplasia; Familial Metaphyseal
Dysplasia. If the cranial features are significant, the disease is also
called craniometaphyseal dysplasia.
NB: Metaphyseal dysplasia and metaphyseal chondrodysplasia are not the
First described by E. Pyle, an American orthopedic surgeon.
About 25 cases have been reported.
The mechanism or cause remain unknown; however,
abnormal tubulation of the bone may play a role.
Made by clinical features and radiographic studies.
Symmetrical expansion of the metaphyses of long bones results in the
so-called “Erlenmeyer flask deformity,” describing the flaring of long
bones (mainly of distal femur and proximal tibia) in combination with
cortical thinning in affected areas. This sign is typical, but not
pathognomonic, because it can also be seen in osteopetrosis, Niemann-Pick,
and Gaucher diseases. Osteoporosis of the long bones with an increased risk
for fractures is common.
The patient may be clinically asymptomatic. The
patients are almost always tall as a result of increased limb length
(especially femur and tibia). The most frequent clinical feature is genu
valgum, which is usually mild but may predispose to fractures. The elbows
may not fully extend, the proximal humerus is abnormally wide, as are the
distal radius and ulna. The widening of the lower end of the femurs may be
palpable. There is a gross defect in metaphyseal modeling. Radiologic
examination of the spine may reveal platyspondyly, which could be attributed
to either the same defect in modeling seen in the metaphyses of the long
bones or to pathological fractures as a result of osteoporosis. Scoliosis
has been reported in some patients. The head is enlarged with diffuse
hyperostosis of the entire cranial vault, bony encroachment on the cranial
foramina (potentially resulting in nerve compression with visual and hearing
impairment/loss), absent or poorly pneumatized paranasal sinus,
significantly thickened bone in the area of the glabella with hypertelorism,
and often obstructed nasal breathing (breathing difficulties during upper
airway infections have been described). Inconsistently, the presence of
deciduous teeth is prolonged with marked cavities and prognathia may be
present. Intelligence and general health are normal.
Assess airway and loose teeth.
Visual and hearing impairment could make communication difficult. Sedative
and anxiolytic premedication, as well as the presence of the primary
caregiver, for induction could be helpful.
Airway management could be difficult
secondary to the potentially grotesque facial features. Careful positioning
is recommended because of an increased risk for fractures secondary to
There are no specific pharmacological
Niemann-Pick Disease: Lysosomal storage
disorder caused by a defect in sphingolipid metabolism and involving brain
Gaucher Disease: Most common form of ...