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Bone island

Summary

A solitary area of mature, lamellar bone located within another bone, usually within an area of cancellous bone.

Patients are generally asymptomatic. These lesions are typically incidental finding on x-ray or other imaging study made for an unrelated reason.
Most are 1 - 2 mm is size, but some can be up to 1 -2 cm. or even more. The lesion is latent, and merges at its margin with the surrounding bone. May be multiple, as in osteopoikilosis.
No treatment is needed. After the diagnosis has been confirmed, the lesion can be observed without treatment.
Complete Information on this Tumor
Introduction and Definition: 

Bone island is also called solitary enostosis. The lesion is a hamartoma, consisting of normal tissue in an abnormal location. It appears as a solitary area of mature, lamellar bone located within another bone, usually within an area of cancellous bone.

X-Ray Appearance and Advanced Imaging Findings: 
Most are 1 - 2 mm is size, but some can be up to 1 -2 cm. or even more. The lesion is latent, and merges at its margin with the surrounding bone. May be multiple, as in osteopoikilosis. Uptake on bone scan is decreased. MRI and CT scans show that the lesion has identical signal intensity and density to cortical bone, allowing the diagnosis to be made without biopsy.
Differential Diagnosis: 
The differential diagnosis includes osteosarcoma, metastasis from prostate cancer or other adenocarcinoma that can cause blastic lesions, and herniation pit/ganglion cyst/old fracture type lesions.
Preferred Biopsy Technique for this Tumor: 
Biopsy is typically not needed.
Histopathology findings: 
Normal, mature, lamellar bone with normal architecture, and no cartilage formation or enchondral ossification.
Treatment Options for this Tumor: 
No treatment is needed. After the diagnosis has been confirmed, the lesion can be observed without treatment.