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Review
. 2018 Jun 28:34:43-49.
doi: 10.1016/j.amsu.2018.06.005. eCollection 2018 Oct.

Unicameral bone cysts: Current concepts

Shahryar Noordin  1 , Salim Allana  2 , Masood Umer  1 , Mujahid Jamil  1 , Kiran Hilal  3 , Nasir Uddin  4
Affiliations
Review

Unicameral bone cysts: Current concepts

Shahryar Noordin et al. Ann Med Surg (Lond). .

Abstract

Unicameral bone cysts (UBC) or simple/solitary bone cysts are benign fluid filled cavities that enlarge over time, resulting in thinning of the bone. Usually these cysts are reported in the metaphyseal areas of long bones with open physes. 85% of UBCs occur almost exclusively in children and adolescents. UBCs are more aggressive in the first decade of life and correspondingly the recurrence rate for these patients is four times that for adolescents. The proximal humerus and femur account for almost 90% of these cases. UBCs are classified as active when they are within 1 cm of the physis and latent as they progress to a diaphyseal location. Differential diagnoses for UBC include aneurysmal bone cyst, fibrous dysplasia, enchondroma, and intraosseous ganglia. By the time of skeletal maturity most UBCs tend to resolve. Nonoperative treatment may be a viable option for many patients with small or symptomatic lesions. Interventions include steroid injection, open curettage and bone grafting, decompression and percutaneous injection of marrow or graft substitutes.

Keywords: Current concepts; Unicameral bone cyst.

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Figures

Fig. 1
Fig. 1
7 years old boy with left fibula unicameral bone cyst. AP & lateral radiograph shows a central cystic cavitation, well demarcated, with cortical thinning and mild expansion.
Fig. 2
Fig. 2
12 years old girl with unicameral bone cyst of Tibia. A, coronal and B, axial CT images show expansile lytic lesion (long arrow) containing septa (small arrow). The lesion has the typical appearance of a UBC.
Fig. 3
Fig. 3
8 years old boy with unicameral bone cyst of distal femur. A) Radiograph shows a central lytic metaphyseal lesion with a thin sclerotic margin. There is a pathologic fracture as well as a “fallen bone” fragment (thick arrow) and periosteal reaction (thin arrow). B) Coronal T2 FS MR in same patient shows hyper-intense lesion with fluid levels (arrow). C) Coronal T1WI MR in the same patient shows a low signal lesion, signal nearly isointense to muscle. (Arrow). D) Coronal T1 C + MR, in same patient shows lesion pronounced rim enhancement. The entire imaging pattern is typical of a UBC.
Fig. 4
Fig. 4
Thin fibrous wall of simple bone cyst focally containing multinucleated giant cells.
Fig. 5
Fig. 5
Focally loose fibroblasts seen in wall of cyst.
Fig. 6
Fig. 6
Characteristic amorphous acellular cementum-like material in wall of cyst.
Fig. 7
Fig. 7
Focal transformation of this cementum-like material into immature bone with osteoblastic rimming.
See this image and copyright information in PMC

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