Unicameral bone cyst: Difference between revisions

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{{CMG}}; {{AE}} {{Rohan}}
{{CMG}}; {{AE}} {{Rohan}}


{{SK}}  
{{SK}} Simple bone cyst; Traumatic bone cyst, UBC


==Overview==
==Overview==
Unicameral bone cyst (UBC) constitute approximately 3% of all [[bone tumors]]. Adolescents and children are most affected by unicameral bone cyst. The age distribution of unicameral bone cyst is between 5-15 years. Men are more commonly affected compared to women, with a 2:1 ratio. In 1942, Jaffe and Lichenstein later recognized it as a distinct entity. The exact [[pathogenesis]] of unicameral bone cyst is not fully understood. Unicameral bone cyst may have association with [[genetic]] abnormalities on [[chromosome 4]], [[Chromosome 6|6]], [[Chromosome 8|8]], [[Chromosome 16|16]], [[Chromosome 21|21]], and both [[Chromosome 12|chromosomes 12]]. The [[bones]] often involved are proximal [[femur]], distal [[tibia]], [[Ilium (bone)|ilium]], [[calcaneus]], and occasionally [[Metacarpus|metacarpals]], [[Phalanx bones|phalanges]], or distal [[radius]]. Unicameral bone cyst typically occur in the [[metaphysis]] adjacent to the physis of the [[long bones]]. The hallmark of UBC is [[pain]], [[swelling]] and pathological [[Bone fracture|fracture]]. The mainstay of treatment for UBC is [[surgery]] in form of [[curettage]] and [[bone grafting]].


==Historical Perspective==
==Historical Perspective==
*In mediveal times, Lagier et al identified a unicameral bonce cyst in the femur from the remains of a child.<ref name="pmid3317251">{{cite journal| author=Lagier R, Kramar C, Baud CA| title=Femoral unicameral bone cyst in a medieval child. Radiological and pathological study. | journal=Pediatr Radiol | year= 1987 | volume= 17 | issue= 6 | pages= 498-500 | pmid=3317251 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=3317251  }} </ref>
*In mediveal times, Lagier et al identified a unicameral bone cyst in the [[femur]] from the remains of a child.<ref name="pmid3317251">{{cite journal| author=Lagier R, Kramar C, Baud CA| title=Femoral unicameral bone cyst in a medieval child. Radiological and pathological study. | journal=Pediatr Radiol | year= 1987 | volume= 17 | issue= 6 | pages= 498-500 | pmid=3317251 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=3317251  }} </ref>
*In 1891, Virchow reported it as “cystic structures” that resulted due to anomalies in the local circulation.<ref name="pmid10951110">{{cite journal| author=Wilkins RM| title=Unicameral bone cysts. | journal=J Am Acad Orthop Surg | year= 2000 | volume= 8 | issue= 4 | pages= 217-24 | pmid=10951110 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=10951110  }} </ref>
*In 1891, Virchow reported it as “cystic structures” that resulted due to anomalies in the local [[circulation]].<ref name="pmid10951110">{{cite journal| author=Wilkins RM| title=Unicameral bone cysts. | journal=J Am Acad Orthop Surg | year= 2000 | volume= 8 | issue= 4 | pages= 217-24 | pmid=10951110 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=10951110  }} </ref>
*In 1942, Jaffe and Lichenstein later recognized it as a distinct entity.<ref>Jaffe HL, Lichtenstein L. Solitary unicameral bone cyst with emphasis on the roentgen picture, the pathologic appearance and the pathogenesis. Arch Surg. 1942. 44:1004-25.</ref>
*In 1942, Jaffe and Lichenstein later recognized it as a distinct entity.<ref>Jaffe HL, Lichtenstein L. Solitary unicameral bone cyst with emphasis on the roentgen picture, the pathologic appearance and the pathogenesis. Arch Surg. 1942. 44:1004-25.</ref>


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==Pathophysiology==
==Pathophysiology==
*The exact pathogenesis of unicameral bone cyst is not fully understood.
*The exact [[pathogenesis]] of unicameral bone cyst is not fully understood.
*Various theories have been proposed concerning the pathogenesis of unicameral bone cyst:
*Various theories have been proposed concerning the [[pathogenesis]] of unicameral bone cyst:
**Blockage in the venous drainage is the most favored mechanism which occurs in a rapidly growing and remodeling portion of cancellous bone.
**Blockage in the [[Venous return|venous drainage]] is the most favored mechanism which occurs in a rapidly growing and remodeling portion of [[cancellous bone]].
**Increased internal pressure of involved bone as compared to normal pressure of bone marrow.<ref>Chigira M., Maehara S., Arita S., Udagawa E. The aetiology and treatment of simple bone cysts. Bone & Joint Journal. 1983;65(5):633–637.</ref>
**Increased internal pressure of involved bone as compared to normal pressure of [[bone marrow]].<ref>Chigira M., Maehara S., Arita S., Udagawa E. The aetiology and treatment of simple bone cysts. Bone & Joint Journal. 1983;65(5):633–637.</ref>
**Lower partial pressure of oxygen of cyst fluid than arterial or venous blood suggesting a venous obstruction.<ref>Chigira M., Maehara S., Arita S., Udagawa E. The aetiology and treatment of simple bone cysts. Bone & Joint Journal. 1983;65(5):633–637.</ref>
**Lower partial pressure of [[oxygen]] of cyst fluid than [[arterial]] or [[venous]] [[blood]] suggesting a [[venous]] obstruction.<ref>Chigira M., Maehara S., Arita S., Udagawa E. The aetiology and treatment of simple bone cysts. Bone & Joint Journal. 1983;65(5):633–637.</ref>
**Increased levels of lysosomal enzymes in the cyst than serum. Enzymes include prostaglandins, interleukin 1β, nitrate and nitrites levels, proteolytic enzymes, tumor necrosis factor ⍺ and interleukins 1β and 6.<ref name="pmid10968539">{{cite journal| author=Komiya S, Inoue A| title=Development of a solitary bone cyst--a report of a case suggesting its pathogenesis. | journal=Arch Orthop Trauma Surg | year= 2000 | volume= 120 | issue= 7-8 | pages= 455-7 | pmid=10968539 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=10968539  }} </ref>
**Increased levels of [[lysosomal]] [[enzymes]] in the cyst than [[serum]]. [[Enzymes]] include [[Prostaglandin|prostaglandins]], interleukin 1β, [[nitrate]] and [[Nitrite|nitrites]] levels, [[proteolytic]] [[enzymes]], [[Tumor necrosis factor|tumor necrosis factor ⍺]] and [[Interleukin|interleukins]] 1β and [[Interleukin 6|6]].<ref name="pmid10968539">{{cite journal| author=Komiya S, Inoue A| title=Development of a solitary bone cyst--a report of a case suggesting its pathogenesis. | journal=Arch Orthop Trauma Surg | year= 2000 | volume= 120 | issue= 7-8 | pages= 455-7 | pmid=10968539 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=10968539  }} </ref>
*Unicameral bone cyst typically occur in the metaphysis adjacent to the physis of the long bones.
*Unicameral bone cyst typically occur in the [[metaphysis]] adjacent to the physis of the [[long bones]].
*The bones often involved are proximal femur, distal tibia, ilium, calcaneus, and occasionally metacarpals, phalanges, or distal radius.
*The [[bones]] often involved are proximal [[femur]], distal [[tibia]], [[Ilium (bone)|ilium]], [[calcaneus]], and occasionally [[Metacarpus|metacarpals]], [[Phalanx bones|phalanges]], or distal [[radius]].


===Genetics===
===Genetics===
*Unicameral bone cyst may have association with genetic abnormalities on chromosome 4, 6, 8, 16, 21, and both chromosomes 12.
*Unicameral bone cyst may have association with [[genetic]] abnormalities on [[chromosome 4]], [[Chromosome 6|6]], [[Chromosome 8|8]], [[Chromosome 16|16]], [[Chromosome 21|21]], and both [[Chromosome 12|chromosomes 12]].
*Translocation t (16; 20) (p11.2; q13) has been found in cases with unicameral bone cyst.
*Translocation t (16; 20) (p11.2; q13) has been found in cases with unicameral bone cyst.


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! align="center" style="background:#DCDCDC;" + |Aneurysmal bone cyst
! align="center" style="background:#DCDCDC;" + |[[Aneurysmal bone cyst]]
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! align="center" style="background:#DCDCDC;" + |Non ossifying fibroma
! align="center" style="background:#DCDCDC;" + |[[Non ossifying fibroma]]
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! align="center" style="background:#DCDCDC;" + |Giant cell tumor
! align="center" style="background:#DCDCDC;" + |[[Giant cell tumor of bone|Giant cell tumor]]
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! align="center" style="background:#DCDCDC;" + |Chondroblastoma
! align="center" style="background:#DCDCDC;" + |[[Chondroblastoma]]
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! align="center" style="background:#DCDCDC;" + |Chondromyxoid Fibroma
! align="center" style="background:#DCDCDC;" + |[[Chondromyxoid Fibroma]]
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! align="center" style="background:#DCDCDC;" + |Osteoblastoma
! align="center" style="background:#DCDCDC;" + |[[Osteoblastoma]]
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! align="center" style="background:#DCDCDC;" + |Telangiectatic osteosarcoma
! align="center" style="background:#DCDCDC;" + |Telangiectatic [[osteosarcoma]]
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==Epidemiology and Demographics==
==Epidemiology and Demographics==
*Unicameral bone cyst constitute approximately 3% of all bone tumors.
*Unicameral bone cyst constitute approximately 3% of all [[bone tumors]].
*Adolescents and children are most affected by unicameral bone cyst.<ref name="pmid24788445">{{cite journal| author=Pretell-Mazzini J, Murphy RF, Kushare I, Dormans JP| title=Unicameral bone cysts: general characteristics and management controversies. | journal=J Am Acad Orthop Surg | year= 2014 | volume= 22 | issue= 5 | pages= 295-303 | pmid=24788445 | doi=10.5435/JAAOS-22-05-295 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=24788445  }} </ref>
*Adolescents and children are most affected by unicameral bone cyst.<ref name="pmid24788445">{{cite journal| author=Pretell-Mazzini J, Murphy RF, Kushare I, Dormans JP| title=Unicameral bone cysts: general characteristics and management controversies. | journal=J Am Acad Orthop Surg | year= 2014 | volume= 22 | issue= 5 | pages= 295-303 | pmid=24788445 | doi=10.5435/JAAOS-22-05-295 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=24788445  }} </ref>
*The age distribution of unicameral bone cyst is between 5-15 years.<ref name="pmid11856945">{{cite journal| author=Biermann JS| title=Common benign lesions of bone in children and adolescents. | journal=J Pediatr Orthop | year= 2002 | volume= 22 | issue= 2 | pages= 268-73 | pmid=11856945 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=11856945  }} </ref>
*The age distribution of unicameral bone cyst is between 5-15 years.<ref name="pmid11856945">{{cite journal| author=Biermann JS| title=Common benign lesions of bone in children and adolescents. | journal=J Pediatr Orthop | year= 2002 | volume= 22 | issue= 2 | pages= 268-73 | pmid=11856945 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=11856945  }} </ref>
*The mean age of the patients with unicameral bone cyst is 9 years.
*The mean age of the patients with unicameral bone cyst is 9 years.
*Men are more commonly affected than women, with a 2:1 ratio.<ref name="pmid4874360">{{cite journal| author=Boseker EH, Bickel WH, Dahlin DC| title=A clinicopathologic study of simple unicameral bone cysts. | journal=Surg Gynecol Obstet | year= 1968 | volume= 127 | issue= 3 | pages= 550-60 | pmid=4874360 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=4874360  }} </ref>
*Men are more commonly affected than women, with a 2:1 ratio.<ref name="pmid4874360">{{cite journal| author=Boseker EH, Bickel WH, Dahlin DC| title=A clinicopathologic study of simple unicameral bone cysts. | journal=Surg Gynecol Obstet | year= 1968 | volume= 127 | issue= 3 | pages= 550-60 | pmid=4874360 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=4874360  }} </ref>
*There is no racial predilection to chondroblastoma.
*There is no racial predilection to unicameral bone cyst.


==Risk Factors==
==Risk Factors==
There are no established risk factors for unicameral bone cyst.
There are no established [[risk factors]] for unicameral bone cyst.


==Screening==
==Screening==
There is insufficient evidence to recommend routine screening for unicameral bone cyst.
There is insufficient evidence to recommend routine [[Screening (medicine)|screening]] for unicameral bone cyst.


==Natural History, Complications, and Prognosis==
==Natural History, Complications, and Prognosis==
*Common complications of unicameral bone cyst (UBC) include:
*Common [[complications]] of unicameral bone cyst (UBC) include:
**Pathological fracture
**Pathological [[Bone fracture|fracture]]
**Premature epiphyseal closure
**Premature [[Epiphyseal plate|epiphyseal]] closure
***Limb-length discrepancy
***[[Limb-length discrepancy]]
***Angular deformity
***[[Angular deformity]]
**Malignant transformation.
**[[Malignant transformation]]
*Prognosis is generally excellent for Unicameral bone cyst.
*[[Prognosis]] is generally excellent for Unicameral bone cyst.
**As a patient approaches skeletal maturity, a unicameral bone cyst will often decrease in size and may heal after growth is complete.
**As a patient approaches [[skeletal]] maturity, a unicameral bone cyst will often decrease in size and may heal after growth is complete.
**Fracture healing usually does not lead to cyst resolution.
**[[Fracture]] healing usually does not lead to cyst resolution.
**It requires close follow up while in active phase due to recurrence and risk of fracture or growth arrest.
**It requires close follow up while in active phase due to recurrence and risk of [[fracture]] or growth arrest.


==Diagnosis==
==Diagnosis==
===Diagnostic Study of Choice===
===Diagnostic Study of Choice===
*Biopsy is the diagnostic study of choice for the diagnosis of unicameral bone cyst.
*[[Biopsy]] is the diagnostic study of choice for the [[diagnosis]] of unicameral bone cyst.
*Biopsy findings include:
*[[Biopsy]] findings include:
*Cyst are lined with thin fibrous lining containing fibrous tissue, giant cells, and hemosiderin pigment.
**[[Cyst]] are lined with thin [[fibrous]] lining containing [[fibrous tissue]], [[giant cells]], and [[hemosiderin]] pigment.
*Inflammatory cells such as lymphocytes may be found in small numbers.
**[[Inflammatory cells]] such as [[Lymphocyte|lymphocytes]] may be found in small numbers.
*Uniform amount of spindle cells without nuclear atypia.
**Uniform amount of [[spindle cells]] without nuclear atypia.


===History and Symptoms===
===History and Symptoms===
*The majority of patients with unicameral bone cyst have a positive history of:
*The majority of patients with unicameral bone cyst have a positive history of:
**Pain
**[[Pain]]
**Swelling
**[[Swelling]]
**Pathological fracture
**Pathological [[Bone fracture|fracture]]
**Neurologic conditions occur often due to compression of either the spinal cord or nerve roots, and lead to: Paralysis Spinal stiffness
**Neurologic conditions occur often due to compression of either the [[spinal cord]] or [[nerve roots]], and leading to [[paralysis]] and spinal [[stiffness]]


===Physical Examination===
===Physical Examination===
Patients with [disease name] usually appear [general appearance]. Physical examination of patients with [disease name] is usually remarkable for [finding 1], [finding 2], and [finding 3].
*Common [[physical examination]] findings of unicameral bone cyst include:
 
**[[Deformity]]
OR
**Decreased [[range of motion]], [[weakness]], or [[stiffness]]
 
**[[Torticollis]]
Common physical examination findings of [disease name] include [finding 1], [finding 2], and [finding 3].
**Occasionally, [[bruit]] over the affected area
 
**Warmth over the affected area
OR
{| align="right"
 
|
The presence of [finding(s)] on physical examination is diagnostic of [disease name].
[[File:Xray UBC.gif|300px|thumb|X-ray showing unicameral bone cyst of left proximal femur.[https://radiopaedia.org/cases/unicameral-bone-cyst-9?lang=us Source: Case courtesy of A.Prof Frank Gaillard, Radiopaedia.org, rID: 10361]]]
 
|}
OR
 
The presence of [finding(s)] on physical examination is highly suggestive of [disease name].
 
===Laboratory Findings===
===Laboratory Findings===
There are no diagnostic laboratory findings associated with unicameral bone cyst.
There are no diagnostic laboratory findings associated with unicameral bone cyst.


===Electrocardiogram===
===Electrocardiogram===
There are no ECG findings associated with unicameral bone cyst.
There are no [[The electrocardiogram|ECG findings]] associated with unicameral bone cyst.


===X-ray===
===X-ray===
There are no x-ray findings associated with [disease name].
*Findings on an [[x-ray]] suggestive of unicameral bone cyst include include:<ref name="pmid5771835">{{cite journal| author=Reynolds J| title=The "fallen fragment sign" in the diagnosis of unicameral bone cysts. | journal=Radiology | year= 1969 | volume= 92 | issue= 5 | pages= 949-53 passim | pmid=5771835 | doi=10.1148/92.5.949 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=5771835  }} </ref><ref name="pmid7226646">{{cite journal| author=McGlynn FJ, Mickelson MR, El-Khoury GY| title=The fallen fragment sign in unicameral bone cyst. | journal=Clin Orthop Relat Res | year= 1981 | volume=  | issue= 156 | pages= 157-9 | pmid=7226646 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=7226646  }} </ref>
 
**Central, [[lytic]], well-demarcated [[metaphyseal]] lesion.
OR
**[[Cystic]] expansion with symmetric thinning of cortices.
 
**"Fallen leaf" is a pathognomic sign seen in pathologic [[fracture]] with fallen cortical fragment in base of empty cyst.  
An x-ray may be helpful in the diagnosis of [disease name]. Findings on an x-ray suggestive of/diagnostic of [disease name] include [finding 1], [finding 2], and [finding 3].
**Trabeculated appearance after multiple [[fractures]].
 
{| align="right"
OR
|
 
[[File:CT UBC.gif|300px|thumb|CT scan showing unicameral bone cyst of left proximal femur.[https://radiopaedia.org/cases/unicameral-bone-cyst-9?lang=us Source: Case courtesy of A.Prof Frank Gaillard, Radiopaedia.org, rID: 10361]]]
There are no x-ray findings associated with [disease name]. However, an x-ray may be helpful in the diagnosis of complications of [disease name], which include [complication 1], [complication 2], and [complication 3].
|}


===Echocardiography or Ultrasound===
===Echocardiography or Ultrasound===
There are no echocardiography/ultrasound  findings associated with [disease name].
There are no [[echocardiography]]/[[ultrasound]] findings associated with unicameral bone cyst.
 
OR
 
Echocardiography/ultrasound  may be helpful in the diagnosis of [disease name]. Findings on an echocardiography/ultrasound suggestive of/diagnostic of [disease name] include [finding 1], [finding 2], and [finding 3].
 
OR
 
There are no echocardiography/ultrasound  findings associated with [disease name]. However, an echocardiography/ultrasound  may be helpful in the diagnosis of complications of [disease name], which include [complication 1], [complication 2], and [complication 3].


===CT scan===
===CT scan===
There are no CT scan findings associated with [disease name].
*[[CT scan]] confirms the [[x-ray]] findings.
 
*In addition, [[CT-scans|CT]] demonstrates internal [[septation]] such as calcified rim, giving an eggshell appearance, which may be completely or partially intact.
OR
*Free fluid levels can also be seen.
 
[Location] CT scan may be helpful in the diagnosis of [disease name]. Findings on CT scan suggestive of/diagnostic of [disease name] include [finding 1], [finding 2], and [finding 3].
 
OR
 
There are no CT scan findings associated with [disease name]. However, a CT scan may be helpful in the diagnosis of complications of [disease name], which include [complication 1], [complication 2], and [complication 3].


===MRI===
===MRI===
There are no MRI findings associated with [disease name].
[[MRI]] findings of unicameral bone cyst include:<ref name="pmid9727265">{{cite journal| author=Maas EJ, Craig JG, Swisher PK, Amin MB, Marcus N| title=Fluid-fluid levels in a simple bone cyst on magnetic resonance imaging. | journal=Australas Radiol | year= 1998 | volume= 42 | issue= 3 | pages= 267-70 | pmid=9727265 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=9727265  }} </ref><ref name="pmid10993540">{{cite journal| author=Margau R, Babyn P, Cole W, Smith C, Lee F| title=MR imaging of simple bone cysts in children: not so simple. | journal=Pediatr Radiol | year= 2000 | volume= 30 | issue= 8 | pages= 551-7 | pmid=10993540 | doi=10.1007/s002470000258 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=10993540  }} </ref><ref name="pmid10627734">{{cite journal| author=Sullivan RJ, Meyer JS, Dormans JP, Davidson RS| title=Diagnosing aneurysmal and unicameral bone cysts with magnetic resonance imaging. | journal=Clin Orthop Relat Res | year= 1999 | volume=  | issue= 366 | pages= 186-90 | pmid=10627734 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=10627734  }} </ref>
 
*Very dark on T1
OR
*Very bright on T2
 
*[[Gadolinium]] shows classic rim enhancement of a cystic lesion
[Location] MRI may be helpful in the diagnosis of [disease name]. Findings on MRI suggestive of/diagnostic of [disease name] include [finding 1], [finding 2], and [finding 3].
{| align="right"
 
|
OR
[[File:MRI UBC.gif|300px|thumb|MRI scan showing unicameral bone cyst of left proximal humerus.[https://radiopaedia.org/cases/unicameral-bone-cyst-10?lang=us Source: Case courtesy of Dr Yasser Asiri, Radiopaedia.org, rID: 65130]]]
 
|}
There are no MRI findings associated with [disease name]. However, a MRI may be helpful in the diagnosis of complications of [disease name], which include [complication 1], [complication 2], and [complication 3].


===Other Imaging Findings===
===Other Imaging Findings===
There are no other imaging findings associated with [disease name].
OR


[Imaging modality] may be helpful in the diagnosis of [disease name]. Findings on an [imaging modality] suggestive of/diagnostic of [disease name] include [finding 1], [finding 2], and [finding 3].
===Bone Scan===
*Increased uptake is observed around the lesion of unicameral bone cyst.
*Findings often demonstrate a halo effect of increased [[radionuclide]] uptake surrounding an area of little uptake.


===Other Diagnostic Studies===
===Other Diagnostic Studies===
There are no other diagnostic studies associated with [disease name].
OR
[Diagnostic study] may be helpful in the diagnosis of [disease name]. Findings suggestive of/diagnostic of [disease name] include [finding 1], [finding 2], and [finding 3].
OR


Other diagnostic studies for [disease name] include [diagnostic study 1], which demonstrates [finding 1], [finding 2], and [finding 3], and [diagnostic study 2], which demonstrates [finding 1], [finding 2], and [finding 3].
===Angiography===
*[[Angiography]] demonstrates a hypervascular area around the unicameral bone cyst.
*An intense diffuse area of persistent contrast accumulation may be visualized without main afferent or efferent [[Blood vessel|vessels]] observed.


==Treatment==
==Treatment==
The mainstay of therapy for unicameral bone cyst is surgery.
The mainstay of therapy for unicameral bone cyst is [[surgery]].


===Medical Therapy===
===Medical Therapy===
Line 244: Line 219:


'''Indications'''
'''Indications'''
*Proximal humerus lesions with pathologic fracture  
*Proximal [[humerus]] lesions with pathologic [[Bone fracture|fracture]]
*Inaccessible Lesions
*Inaccessible lesions


===Aspiration and Methylprednisolone Acetate Injection===
===Aspiration and Methylprednisolone Acetate Injection===


'''Indications'''
'''Indications'''
*Active cysts which are communicating with physis.
*Active [[Cyst|cysts]] which are communicating with physis.


'''Technique'''
'''Technique'''
*Usually requires several injections, especially in very young children.
*Usually requires several injections, especially in very young children.
*Bone marrow injections have recently been reported to be effective.  
*[[Bone marrow]] injections have recently been reported to be effective.  


===Surgery===
===Surgery===
Surgery is the mainstay of treatment for unicameral bone cyst.
[[Surgery]] is the mainstay of treatment for unicameral bone cyst.


===Curettage and bone grafting with internal fixation===
===Curettage and bone grafting with internal fixation===


'''Indications'''
'''Indications'''
*Symptomatic latent cysts that have not responded to steroid injections.
*[[Symptomatic]] latent [[Cyst|cysts]] that have not responded to [[steroid]] injections.
*Latent cysts located in areas such as proximal femur where structural integrity is a concern and at risk for fracture and osteonecrosis.
*Latent [[Cyst|cysts]] located in areas such as proximal [[femur]] where structural integrity is a concern and at risk for [[fracture]] and [[osteonecrosis]].
*Lesions with a pathologic fracture that have a higher rate of re-fracture and malunion when treated nonoperatively.
*Lesions with a pathologic [[Bone fracture|fracture]] that have a higher rate of re-[[Bone fracture|fracture]] and malunion when treated nonoperatively.


'''Contraindications'''
'''Contraindications'''
*Active lesions which are in communication with physis, which may result in growth arrest.
*Active lesions which are in communication with physis, which may result in growth arrest.
===Treatment Response Evaluation===
Neer rating system for the purposes of evaluating treatment response are as follows:<ref name="pmid15580740">{{cite journal| author=Neer CS, Francis KC, Marcove RC, Terz J, Carbonara PN| title=Treatment of unicameral bone cyst. A follow-up study of one hundred seventy-five cases. | journal=J Bone Joint Surg Am | year= 1966 | volume= 48 | issue= 4 | pages= 731-45 | pmid=15580740 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=15580740  }} </ref>
*Excellent – Complete obliteration of the [[cyst]].
*Residual defect – One or more static [[cyst]] like areas with good reestablishment of [[bone]] strength.
*Reoperation – Subsequent operation required because of recurrence.


===Primary Prevention===
===Primary Prevention===
There are no established measures for the primary prevention of unicameral bone cyst.
There are no established measures for the [[primary prevention]] of unicameral bone cyst.


===Secondary Prevention===
===Secondary Prevention===
There are no established measures for the secondary prevention of unicameral bone cyst.
There are no established measures for the [[secondary prevention]] of unicameral bone cyst.


==References==
==References==

Latest revision as of 17:40, 3 April 2019

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Rohan A. Bhimani, M.B.B.S., D.N.B., M.Ch.[2]

Synonyms and keywords: Simple bone cyst; Traumatic bone cyst, UBC

Overview

Unicameral bone cyst (UBC) constitute approximately 3% of all bone tumors. Adolescents and children are most affected by unicameral bone cyst. The age distribution of unicameral bone cyst is between 5-15 years. Men are more commonly affected compared to women, with a 2:1 ratio. In 1942, Jaffe and Lichenstein later recognized it as a distinct entity. The exact pathogenesis of unicameral bone cyst is not fully understood. Unicameral bone cyst may have association with genetic abnormalities on chromosome 4, 6, 8, 16, 21, and both chromosomes 12. The bones often involved are proximal femur, distal tibia, ilium, calcaneus, and occasionally metacarpals, phalanges, or distal radius. Unicameral bone cyst typically occur in the metaphysis adjacent to the physis of the long bones. The hallmark of UBC is pain, swelling and pathological fracture. The mainstay of treatment for UBC is surgery in form of curettage and bone grafting.

Historical Perspective

  • In mediveal times, Lagier et al identified a unicameral bone cyst in the femur from the remains of a child.[1]
  • In 1891, Virchow reported it as “cystic structures” that resulted due to anomalies in the local circulation.[2]
  • In 1942, Jaffe and Lichenstein later recognized it as a distinct entity.[3]

Classification

Unicameral bone cyst can be classified based on imaging findings.

Enneking (MSTS) Staging System

  • The Enneking surgical staging system (also known as the MSTS system) for benign musculoskeletal tumors based on radiographic characteristics of the tumor host margin.[4]
  • It is widely accepted and routinely used classification.
Stages Description
1 Latent: Well demarcated borders
2 Active: Indistinct borders
3 Aggressive: Indistinct borders

Pathophysiology

Genetics

  • Unicameral bone cyst may have association with genetic abnormalities on chromosome 4, 6, 8, 16, 21, and both chromosomes 12.
  • Translocation t (16; 20) (p11.2; q13) has been found in cases with unicameral bone cyst.

Causes

There are no established causes for unicameral bone cyst.

Differentiating Unicameral Bone Cyst from Other Diseases

Unicameral bone cyst must be differentiated from following bone disorders:

Disease Bubbly lytic lesion on x-ray Lakes of Blood on histology Diagnosis Treatment is curretage and bone grafting
Unicameral bone cyst + - Radiology and biopsy -
Aneurysmal bone cyst + + Radiology and biopsy +
Non ossifying fibroma + - Radiology and biopsy -
Giant cell tumor - - Radiology and Biopsy +
Chondroblastoma - - Biopsy +
Chondromyxoid Fibroma - - Radiology and biopsy +
Osteoblastoma - - Radiology and biopsy +
Telangiectatic osteosarcoma - + Radiology and biopsy -

Epidemiology and Demographics

  • Unicameral bone cyst constitute approximately 3% of all bone tumors.
  • Adolescents and children are most affected by unicameral bone cyst.[8]
  • The age distribution of unicameral bone cyst is between 5-15 years.[9]
  • The mean age of the patients with unicameral bone cyst is 9 years.
  • Men are more commonly affected than women, with a 2:1 ratio.[10]
  • There is no racial predilection to unicameral bone cyst.

Risk Factors

There are no established risk factors for unicameral bone cyst.

Screening

There is insufficient evidence to recommend routine screening for unicameral bone cyst.

Natural History, Complications, and Prognosis

Diagnosis

Diagnostic Study of Choice

History and Symptoms

Physical Examination

X-ray showing unicameral bone cyst of left proximal femur.Source: Case courtesy of A.Prof Frank Gaillard, Radiopaedia.org, rID: 10361

Laboratory Findings

There are no diagnostic laboratory findings associated with unicameral bone cyst.

Electrocardiogram

There are no ECG findings associated with unicameral bone cyst.

X-ray

  • Findings on an x-ray suggestive of unicameral bone cyst include include:[11][12]
    • Central, lytic, well-demarcated metaphyseal lesion.
    • Cystic expansion with symmetric thinning of cortices.
    • "Fallen leaf" is a pathognomic sign seen in pathologic fracture with fallen cortical fragment in base of empty cyst.
    • Trabeculated appearance after multiple fractures.
CT scan showing unicameral bone cyst of left proximal femur.Source: Case courtesy of A.Prof Frank Gaillard, Radiopaedia.org, rID: 10361

Echocardiography or Ultrasound

There are no echocardiography/ultrasound findings associated with unicameral bone cyst.

CT scan

  • CT scan confirms the x-ray findings.
  • In addition, CT demonstrates internal septation such as calcified rim, giving an eggshell appearance, which may be completely or partially intact.
  • Free fluid levels can also be seen.

MRI

MRI findings of unicameral bone cyst include:[13][14][15]

  • Very dark on T1
  • Very bright on T2
  • Gadolinium shows classic rim enhancement of a cystic lesion
MRI scan showing unicameral bone cyst of left proximal humerus.Source: Case courtesy of Dr Yasser Asiri, Radiopaedia.org, rID: 65130

Other Imaging Findings

Bone Scan

  • Increased uptake is observed around the lesion of unicameral bone cyst.
  • Findings often demonstrate a halo effect of increased radionuclide uptake surrounding an area of little uptake.

Other Diagnostic Studies

Angiography

  • Angiography demonstrates a hypervascular area around the unicameral bone cyst.
  • An intense diffuse area of persistent contrast accumulation may be visualized without main afferent or efferent vessels observed.

Treatment

The mainstay of therapy for unicameral bone cyst is surgery.

Medical Therapy

Immobilization

Indications

Aspiration and Methylprednisolone Acetate Injection

Indications

  • Active cysts which are communicating with physis.

Technique

  • Usually requires several injections, especially in very young children.
  • Bone marrow injections have recently been reported to be effective.

Surgery

Surgery is the mainstay of treatment for unicameral bone cyst.

Curettage and bone grafting with internal fixation

Indications

Contraindications

  • Active lesions which are in communication with physis, which may result in growth arrest.

Treatment Response Evaluation

Neer rating system for the purposes of evaluating treatment response are as follows:[16]

  • Excellent – Complete obliteration of the cyst.
  • Residual defect – One or more static cyst like areas with good reestablishment of bone strength.
  • Reoperation – Subsequent operation required because of recurrence.

Primary Prevention

There are no established measures for the primary prevention of unicameral bone cyst.

Secondary Prevention

There are no established measures for the secondary prevention of unicameral bone cyst.

References

  1. Lagier R, Kramar C, Baud CA (1987). "Femoral unicameral bone cyst in a medieval child. Radiological and pathological study". Pediatr Radiol. 17 (6): 498–500. PMID 3317251.
  2. Wilkins RM (2000). "Unicameral bone cysts". J Am Acad Orthop Surg. 8 (4): 217–24. PMID 10951110.
  3. Jaffe HL, Lichtenstein L. Solitary unicameral bone cyst with emphasis on the roentgen picture, the pathologic appearance and the pathogenesis. Arch Surg. 1942. 44:1004-25.
  4. Jawad MU, Scully SP (2010). "In brief: classifications in brief: enneking classification: benign and malignant tumors of the musculoskeletal system". Clin Orthop Relat Res. 468 (7): 2000–2. doi:10.1007/s11999-010-1315-7. PMC 2882012. PMID 20333492.
  5. Chigira M., Maehara S., Arita S., Udagawa E. The aetiology and treatment of simple bone cysts. Bone & Joint Journal. 1983;65(5):633–637.
  6. Chigira M., Maehara S., Arita S., Udagawa E. The aetiology and treatment of simple bone cysts. Bone & Joint Journal. 1983;65(5):633–637.
  7. Komiya S, Inoue A (2000). "Development of a solitary bone cyst--a report of a case suggesting its pathogenesis". Arch Orthop Trauma Surg. 120 (7–8): 455–7. PMID 10968539.
  8. Pretell-Mazzini J, Murphy RF, Kushare I, Dormans JP (2014). "Unicameral bone cysts: general characteristics and management controversies". J Am Acad Orthop Surg. 22 (5): 295–303. doi:10.5435/JAAOS-22-05-295. PMID 24788445.
  9. Biermann JS (2002). "Common benign lesions of bone in children and adolescents". J Pediatr Orthop. 22 (2): 268–73. PMID 11856945.
  10. Boseker EH, Bickel WH, Dahlin DC (1968). "A clinicopathologic study of simple unicameral bone cysts". Surg Gynecol Obstet. 127 (3): 550–60. PMID 4874360.
  11. Reynolds J (1969). "The "fallen fragment sign" in the diagnosis of unicameral bone cysts". Radiology. 92 (5): 949-53 passim. doi:10.1148/92.5.949. PMID 5771835.
  12. McGlynn FJ, Mickelson MR, El-Khoury GY (1981). "The fallen fragment sign in unicameral bone cyst". Clin Orthop Relat Res (156): 157–9. PMID 7226646.
  13. Maas EJ, Craig JG, Swisher PK, Amin MB, Marcus N (1998). "Fluid-fluid levels in a simple bone cyst on magnetic resonance imaging". Australas Radiol. 42 (3): 267–70. PMID 9727265.
  14. Margau R, Babyn P, Cole W, Smith C, Lee F (2000). "MR imaging of simple bone cysts in children: not so simple". Pediatr Radiol. 30 (8): 551–7. doi:10.1007/s002470000258. PMID 10993540.
  15. Sullivan RJ, Meyer JS, Dormans JP, Davidson RS (1999). dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=10627734 "Diagnosing aneurysmal and unicameral bone cysts with magnetic resonance imaging" Check |url= value (help). Clin Orthop Relat Res (366): 186–90. PMID 10627734.
  16. Neer CS, Francis KC, Marcove RC, Terz J, Carbonara PN (1966). "Treatment of unicameral bone cyst. A follow-up study of one hundred seventy-five cases". J Bone Joint Surg Am. 48 (4): 731–45. PMID 15580740.


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