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MYOSITIS OSSIFICANS
Authored By: Keith Fischer and Shane Inoue.
Patient: 12 year old female
History: Admitted 2 days prior to the bone scan with left arm swelling and pain that was first noticed about 1 week ago, but has worsened over the 24 hours just prior to admission.  Upon admission, an MRI of the left upper extremity was done and interpreted as a deltoid muscle mass, likely rhabdomyosarcoma.
Image Size:[small][as-submitted]

Fig. 1
Whole body bone images.

Fig. 2
Spot Images.

Fig. 3
L shouler XR interpreted as normal.

Fig. 4
T1 pre- and post-contrast images demonstrating enhancement of the deltoid images.
Image Size:[small][as-submitted]

Findings: Increased tracer uptake in the left proximal arm. The findings are consistent with a mass in the left shoulder associated with the proximal humerus.
DDx: Causes of soft tissue uptake:

Tumor
Inflammation
dystrophic calcification
dermatomyositis
enthesiopathies (e.g. calcific tendonitis)
post-operative scars
amyloid. 
Diagnosis: Myositis Ossificans, confirmed by pathology.
General Discussion: Traumatic injury to muscle leading to calcifying hematomas or myositis ossificans can also result in soft tissue uptake, as can recently infarcted skeletal muscle (rhabdomyolysis).  Calcification within soft-tissue neoplasms can result in increased soft-tissue activity.  Additional causes of soft-tissue activity include dystrophic calcification, dermatomyositis, enthesiopathies (e.g. calcific tendonitis), post-operative scars, inflammation, and amyloid. 
References: Mettler, FA, Guiberteau, MJ.  Essentials of Nuclear Medicine Imgaing, 5th ed.  Philadelphia, Saunders, 2006.
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Additional Details:

Case Number: 105235Owner(s): Keith Fischer and Shane InoueLast Updated: 02-07-2013
Anatomy: Skeletal System   Pathology: Non-Infectious Inflammatory Disease
Modality: Conventional Radiograph, MR, Nuc MedAccess Level: Readable by all users, writable by NucMed Certifiers
Keywords: myositis ossificans

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Certified by Keith Fischer on 06-26-2009

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