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Summary:A 3-year-old girl came to the radiology department from the genetics clinic, where she was referred because of widening of the bonesin her legs. There was concern that other bones were involved. The patient was delivered by spontaneous vaginal delivery at term, after an uneventful pregnancy and weighed 6 pounds, 12 ounces.She had a history of genu valgum, which was noticed at 13 months of age. Her prior medical and surgical histories were not significant. There was no history of bony fractures, hip dislocation or mental retardation.She had a maternal half-sister who was 12 years old and healthy and the patient also had a younger 2-year-old full sister who had started to show the same signs of widening of the leg bones and genu valgum.There was no history of consanguinity. Her developmental history was also within normal limits.Physical examination revealed her weight to be slightly beneath the 50th percentile and her height was just above the 50th percentile.She had no facial dysmorphism, with no obvious clinodactyly, polydactyly or syndactyly. No dental caries were noted. There was noevidence of scoliosis or platyspondyly.Diagnosis:Pyle-type metaphyseal dysplasia (or Pyle’s disease)Differential diagnosis: Chronic anemia (e.g. Sickle-cell disease), osteopetrosis, Gaucher disease and Niemann-Pick disease.Imaging findings:Skeletal survey revealed a mildly hyperostotic skull, with mild frontal bossing. There was metaphyseal widening of the long bones. Lateral bowing of the tibiae produced an S-shaped configuration (Figures 1C and 1D). However, the spine was normal (Figure 5).Discussion:Pyle-type metaphyseal dysplasia is an extremely uncommon and rare genetic skeletal disorder inherited in an autosomal-recessive pattern (Gorlin et al. 1970.1 This means that both parents are unaffected, but there is a 25% chance the affected alleles will pass to a developing embryo and produce the widened biones. The actual gene or genetic defect is unknown, and cannot therefore be tested. The striking radiographic manifestations contrast with the relatively normal clinical features. Genu valgum is the only consistent abnormality.Pyle first described the skeletal anomaly in 1931. Less than 35 genuine cases have since been reported.Pyle-type metaphyseal dysplasia is clinically, radiographically and genetically distinct from craniometaphyseal dysplasia, a relatively common condition with which it has been confused. Pyle-type metaphyseal dysplasia must be distinguished and separated from craniometaphyseal dysplasia, for prognostication, since deafness, facial paralysis and occasional impairment of vision may result from cranial nerve compression in the latter, whereas, they are unusual in the former.1,2Bone fragility and spinal malalignment or scoliosis is infrequent but are well-documented complications.3,4 Carious and misplaced teeth,4 and patchy sclerosis of the cranial vault with associated moderate supraorbital prominence and prognathism are features that have been reported in Pyle-type metaphyseal dysplasia.3Genetic considerations are also relevant, as craniometaphyseal dysplasia is transmitted as an autosomal dominant, whereas, inheritance in Pyle-type metaphyseal dysplasia is autosomal recessive.5In Pyle-type metaphyseal dysplasia there are gross abnormalities of the tubular bone modeling, with associated mild sclerosis of thecranium. Prominent radiographic features in the long tubular bones consist of splaying of the metaphyses with relative constriction ofthe diaphyses. The changes are most obvious in the distal femora, where the appearance has been likened to an “Erlenmeyer flask.” Failure of modeling may also be seen in the short tubular bones, with widening of the medial ends of the clavicles, sternal ends of theribs and pubic bones.CONCLUSIONIn spite of the striking radiographic manifestations, there are a few clinical stigmata and the condition has a benign course. 1. Gorlin RJ, Koszalk
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CASE SUMMARYA 3-year-old girl came to the radiol-
ogy department from the genetics clinic,where she was referred because ofwidening of the bones in her legs. Therewas concern that other bones wereinvolved.
The patient was delivered by sponta-neous vaginal delivery at term, after an uneventful pregnancy and weighed 6 pounds, 12 ounces.
She had a history of genu valgum,which was noticed at 13 months of age.Her prior medical and surgical histo-ries were not significant. There was nohistory of bony fractures, hip disloca-tion or mental retardation.
She had a maternal half-sister whowas 12 years old and healthy and thepatient also had a younger 2-year-oldfull sister who had started to show thesame signs of widening of the leg bonesand genu valgum.
There was no history of consanguin-ity. Her developmental history was alsowithin normal limits.
Physical examination revealed herweight to be slightly beneath the 50thpercentile and her height was just abovethe 50th percentile.
She had no facial dysmorphism,with no obvious clinodactyly, poly-dactyly or syndactyly. No dental carieswere noted. There was no evidence ofscoliosis or platyspondyly.
IMAGING FINDINGSSkeletal survey revealed a mildly
hyperostotic skull, with mild frontalbossing. There was metaphyseal widen-ing of the long bones. Lateral bowing ofthe tibiae produced an S-shaped config-uration (Figures 1C and 1D). However,the spine was normal (Figure 5).
DIAGNOSISPyle-type metaphyseal dysplasia (or
Pyle’s disease)
Differential diagnosis: Chronic ane-mia (e.g. Sickle-cell disease), osteopetro-sis, Gaucher disease and Niemann-Pick disease.
DISCUSSIONPyle-type metaphyseal dysplasia is
an extremely uncommon and raregenetic skeletal disorder inherited in anautosomal-recessive pattern (Gorlin etal. 1970.1 This means that both parentsare unaffected, but there is a 25%
40A ! APPLIED RADIOLOGY© www.appliedradiology.com July–August 2009
R A D I O L O G I C A L C A S E
Adejimi O. Adeniji, MD
Pyle-type metaphyseal dysplasia
FIGURE 1. “Erlenmeyer flask” femoral deformity in the right (A )and left (B) femurs with lat-eral S-shaped bowing of the right (C) and left (D) tibiae.
A B C D
www.appliedradiology.com APPLIED RADIOLOGY© ! 40BJuly–August 2009
chance the affected alleles will pass to adeveloping embryo and produce thewidened biones. The actual gene orgenetic defect is unknown, and cannottherefore be tested. The striking radi-ographic manifestations contrast withthe relatively normal clinical features.Genu valgum is the only consistentabnormality.
Pyle first described the skeletalanomaly in 1931. Less than 35 genuinecases have since been reported.
Pyle-type metaphyseal dysplasia isclinically, radiographically and geneti-cally distinct from craniometaphysealdysplasia, a relatively common condi-tion with which it has been confused.Pyle-type metaphyseal dysplasia must
be distinguished and separated fromcraniometaphyseal dysplasia, for prog-nostication, since deafness, facialparalysis and occasional impairment ofvision may result from cranial nervecompression in the latter, whereas,they are unusual in the former.1,2
Bone fragility and spinal malalign-ment or scoliosis is infrequent but are
R A D I O L O G I C A L C A S E
FIGURE 2. Undertubulation of both humeri in their proximal two-thirds.
FIGURE 3. Undertubulation of the distaltwo-thirds of the radius and ulna. Inciden-tally noted, is lucency in the left wrist (rightarrow), which could be either due to a vac-uum phenomenon or artifactual.
A B
A B A B
FIGURE 4. Skull radiographs, AP and lateral views. There is mild sclerosis of the skull basewith prominence of the frontal bones
40C ! APPLIED RADIOLOGY© www.appliedradiology.com July–August 2009
well-documented complications.3,4
Carious and misplaced teeth,4 andpatchy sclerosis of the cranial vaultwith associated moderate supraorbitalprominence and prognathism are fea-tures that have been reported in Pyle-type metaphyseal dysplasia.3
Genetic considerations are also rel-evant, as craniometaphyseal dysplasiais transmitted as an autosomal domi-nant, whereas, inheritance in Pyle-typemetaphyseal dysplasia is autosomalrecessive.5
In Pyle-type metaphyseal dysplasiathere are gross abnormalities of thetubular bone modeling, with associatedmild sclerosis of the cranium. Promi-nent radiographic features in the longtubular bones consist of splaying of themetaphyses with relative constrictionof the diaphyses. The changes are mostobvious in the distal femora, where theappearance has been likened to an“Erlenmeyer flask.” Failure of model-ing may also be seen in the short tubu-lar bones, with widening of the medialends of the clavicles, sternal ends ofthe ribs and pubic bones.
CONCLUSION:In spite of the striking radiographic
manifestations, there are a few clinicalstigmata and the condition has abenign course.
REFERENCES1.Gorlin RJ, Koszalka MF, Spranger J. Pyle’s dis-ease (familial metaphyseal dysplasia. A presenta-tion of two cases and argument for its separationfrom craniometaphyseal dyslasia. J Bone JointSurg Am. 1970;52(2):347-354.2. Mabille JP, Benoit JP, Castera D. Dysplasiemetaphysaire de Pyle. Ann of Radiol (Paris).1973;16:723-730.3.Pyle, E. A case of unusual bone development. JBone Joint Surg Am. 1931;13:874-876.4.Bawkin, H, Krida, A. Familial metaphyseal dys-plasia. American Journal of Diseases of Children.1937;53:1521-1527.5. Raad MS, Beighton, P. Autosomal recessiveinheritance of metaphyseal dysplasia (Pyle dis-ease). Clin Genet. 1978;14: 251-256.
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FIGURE 5. Normal lateral view of the spine.
Prepared by Adejimi O. Adeniji,MD, Divisional Chairman, Pedi-atric Radiology, John Stroger Hos-pital of Cook County, Chicago, IL.
