Mickey Mouse sign of Paget's (bone scan)

Case contributed by Kevin Banks
Diagnosis almost certain

Presentation

Incidental finding on CT.

Patient Data

Age: 75 years
Gender: Female

CT performed for abdominal pain shows an incidental finding of diffuse sclerosis and coarse trabeculations of the T12 vertebral body and posterior elements.

Nuclear medicine

Bone scan obtained for further evaluation of T12 lesion shows moderately increased uptake involving the body, posterior elements, and spinous process. On posterior view, the symmetric uptake of the posterior elements (both pedicles and lamina with midline spinous process inferiorly) forms an inverted v-shaped triangle of 3 dots and has been coined the 'Mickey Mouse' sign and is highly suggestive of Paget's.

No other sites of potential Paget's are seen on the bone scan.

Degenerative osteoblastic activity is present in the right knee, shoulders, sternoclavicular joints, wrists/hands and ankles/feet.

Case Discussion

Tc-99m MDP or HDP bone scintigraphy is highly sensitive for the detection of Paget's disease. It is typically manifest as increased radiotracer uptake, but may occasionally be negative in its late quiescent phase.

Paget's disease is usually not encountered until after age 40.

It is comprised of 3 phases

  • lytic - osteoclasts predominate

  • mixed - active osteoclasts and osteoblasts

  • blastic - osteoblasts predominate

Sites of involvement include: skull, spine, pelvis, and proximal long bones.

The majority of cases are polyostotic with less than a third of cases being monostotic.

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