Case Author(s): Feiyu Xue, M.D., Ph.D. and Keith C. Fischer, M.D. , 6/29/04 . Rating: #D2, #Q3
Diagnosis: Rare expansile bone dysplasia
Brief history:
12-year-old boy with a history of rare expansile bone dysplasia.
Images:
Whole body bone scintigraphy
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View second image(ct).
CT bone window
Full history/Diagnosis is available below
Diagnosis: Rare expansile bone dysplasia
Full history:
12-year-old boy with a history of expansile bone dysplasia of uncertain etiology. The patient was found to have a skeletal dysplasia when he was in-utero at six months. The disease is characterized by marked osteopenia and diffuse expansile bones, most severe in the extremities. He also suffers with frozen joints, most severe in the elbows and knees with bony ankylosis. He has a history of multiple fractures from fragile bones.
Radiopharmaceutical:
7.4 mCi MDP i.v.
Findings:
There is widening of the bones, noticeable in the bony pelvis, humeri and femurs, bilaterally. There is severe deformity in the lower extremities. The legs are in a fixed crossed position bilaterally, due to ankylosis at the knees. There are multiple foci of increased uptake, consistent with fractures of various age. Uptake in the right forearm may be secondary to fracture with adjacent myositis ossificans. A computed tomography of the lower extremities showed heterotopic calcifications in the corresponding areas (not shown here).
A bone window on the pelvic CT demonstrates contical thinning and expansion in the pelvis and femurs. There is severe deformity of the bony pelvis and femurs.
Discussion:
This patient has a rare expansile bone dysplasia of uncertain etiology which was discovered in-utero. Some speculate that he may have familial expansile osteolysis. However, this patient does have accompanied deafness and loss of dentition as a result of middle ear and jaw abnormalities. His disease also involves the axial skeleton (pelvis), which familial expansile osteolysis usually spares. The exact diagnosis can not be made based on the scintigraphic appearance in this case. However, it is important to consider a broad category of disease when a difficult case is encountered. A congenital condition (i.e., osteogenesis imperfecta) is the most likely cause of the scintigraphic findings here. Other considerations including trauma (child abuse), neoplasm, and metabolic bone disease are much less likely.
Reference:
Palenzuela L, Vives-Bauza C, Fernandez-Cadenas I, Meseguer A, Font N, Sarret E, Schwartz S, Andreu AL. Familial expansile osteolysis in a large Spanish kindred resulting from an insertion mutation in the TNFRSF11A gene. J Med Genet. 2002 Oct;39(10):E67.
Whyte MP, Hughes AE. Expansile skeletal hyperphosphatasia is caused by a 15-base pair tandem duplication in TNFRSF11A encoding RANK and is allelic to familial expansile osteolysis. J Bone Miner Res. 2002 Jan;17(1):26-9.
Major teaching point(s):
In a pediatric patient, think congenital bone disorder when a bizzare bone scan is seen.
Differential Diagnosis List
Congenital bone disorder
ACR Codes and Keywords:
References and General Discussion of Bone Scintigraphy (Anatomic field:Skeletal System, Category:Other generalized systemic disorder)
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Case number: bs142
Copyright by Wash U MO
