The evaluation of SPECT/CT bone scintigraphy in metastatic fibrous dysplasia

Fibrous dysplasia is a rare benign bone disorder characterized by the fibrous tissue containing trabeculae of non-lamellar bone (woven bone) and occupying normal medullary spaces. The uptake of the radiotracer in the affected bone is variable, and specificity is too low to diagnose fibrous dysplasia in the bone scan.

We are presenting four cases with monostotic fibrous dysplasia which were detected incidentally on the routine planar bone scan while being investigated for a metastatic cancer work-up. During a cancer work-up at our institution, we find lesions of fibrous dysplasia showing significantly increased uptake on the bone scan which may mimic metastatic bone lesions.

The SPECT/CT increases diagnostic confidence and improves accuracy and specificity of a planar bone scan. These cases were all asymptomatic at the one-year follow-up The subsequent bone scan and radiography studies have revealed no progression of these bone lesions.

The SPECT/CT images increase the diagnostic accuracy of the bone scan, which may avoid unnecessary surgery or overtreatment of fibrous dysplasia as bone metastasis. Abbreviation: SPECT/CT = single photon emission computed tomography/computed tomography.