J Korean Bone Joint Tumor Soc.  2010 Jun;16(1):47-50. 10.5292/jkbjts.2010.16.1.47.

Role of MRI and Plain Radiograph to Diagnose Fibrous Dysplasia Mimicking Metastasis on PET/CT in a Patient with Breast Cancer

• Cho SM
• Jee WH
• Yoo IR
• Lee A
• Chung YG

• KMID: 2006342
• DOI: http://doi.org/10.5292/jkbjts.2010.16.1.47

Abstract

Fibrous dysplasia is a common benign disorder of bone in which normal bone marrow is replaced with fibro-osseous tissue. As PET/CT is increasingly used for the staging of different malignant disease, incidentally found fibrous dysplasia with increased FDG uptake may mimic metastasis. We report on a 46-year-old woman with fibrous dysplasia who underwent PET/CT because of suspected recurrence of breast cancer and was misdiagnosed as a bony metastasis with a focal FDG uptake on left proximal femur. This lesion was interpreted as fibrous dysplasia based on MRI in addition to the plain radiographs. We conclude that MRI in addition to radiography may help to differentiate fibrous dysplasia mimicking metastasis on PET/CT in the patients with malignancy.

Keyword

fibrous dysplasia; PET/CT; MRI

MeSH Terms

Bone Marrow
Breast
Breast Neoplasms
Female
Femur
Humans
Hydrazines
Middle Aged
Neoplasm Metastasis
Recurrence
Hydrazines

Figure

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  Figure 1. A 46-year-old woman with breast cancer. Bone scintigraphy (A) shows a focal hot uptake (arrow) in left proximal femur. PET/CT (B) shows a focal FDG uptake (arrow) in left proximal femur and was mis-interpreted as a single metastasis from breast cancer.

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  Figure 2. Radiograph in a 46-year-old woman shows an intramedullary lesion with a diffuse sclerotic lesion (arrow) on left proximal femur.

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  Figure 3. A 46-year-old woman who underwent MRI for intermittent left hip pain after radiation for one month. Left proximal femoral lesion was interpreted as a fibrous dysplasia based on MR findings. T1-weighted (A) and T2-weighted (B) coronal images show a well-defined hypointense lesion (arrows in A and B) in left proximal femur. Fat-suppressed T2-weighted coronal image (C) shows moderate perilesional hyperintense signal (arrowheads) on the left proximal femur suggesting post-radiation edema. Contrast-enhanced T1-weighted coronal image (D) shows mild contrast enhancement in the mass (arrow). Axial fat-suppressed contrast-enhanced T1-weighted image (E) also shows mild contrast enhancement in the mass. Adjacent muscles in the medial compartment of the thigh shows relatively well-demarcated contrast enhancement, suggesting post-radiation edema.

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  Figure 4. In microscopic examination, fibrous tissue blended into the bone spicules, which had irregular shapes and imperceptible osteoblast rimming (H&E ×100).

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