Myofascial Pain Syndrome on Tc99m MDP Bone Scintigraphy

Sir,

A 45-year-old male presented with upper back pain of 1 month duration. The only relevant finding in the clinical history was that he has been using a computer with a keyboard for extended number of hours each day for years. Chest X-ray posteroanterior view showed soft tissue swelling and calcification in the right axillary region [Figure 1]. ^99mTc-Methylene Diphosphonate skeletal scintigraphy showed abnormal radiopharmaceutical localization at multiple sites in the skeleton indicating skeletal metastasis. Following computed tomography (CT) of the chest, biopsy of the lung lesion reported adenocarcinoma of lung. In the ^99mTc-MDP skeletal scintigraphy, abnormal soft tissue localization was also seen in the region of the teres major muscles, bilaterally, more on the right side [Figure 2]. Magnetic resonance imaging confirmed this soft tissue process in the right shoulder. These findings were consistent with rhabdomyolysis.

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Figure 1 Chest X-ray: soft tissue calcification and swelling (arrow)

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Figure 2 99mTc-MDP skeletal scintigraphy: skeletal metastasis and soft tissue uptake in Teres major muscles, bilaterally: right > left (arrows)

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Rhabdomyolysis of the Teres muscles appears to be a very rare occurrence, and has been reported as a sports injury[1] after transcatheter chemoembolization,[2] and as an incidental finding.[3] In the present case, rhabdomyolysis of the Teres muscles was seen in the clinical setting of skeletal metastasis in an unknown primary, which was later diagnosed as adenocarcinoma of the lung.