PMC8023327_01
Ultrasonography of left forearm before the diagnosis of focal myositis.
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Ultrasonography was performed and showed hypo-echoic area in superficial fascia layer of the left forearm ( Figure 1 ). Ultrasonography guided incisional muscle biopsy were performed.
(A): left forearm biopsy, HE x 100. (B): left forearm biopsy, HE x 200. (C): Protrusion lesion biopsy of left elbow, HE x 100. (D): Protrusion lesion biopsy of left elbow, HE x 400.
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Muscle biopsy ( Figures 2A, B  ) showed focal muscle fiber degeneration, increased perimysial cells, and a few inflammatory cells infiltrate around the interstitial blood vessels.
Protrusion lesion of left elbow.
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But since then left forearm swelling was getting worse, accompanied with protrusion lesion at left elbow ( Figure 3 ) and elevated skin temperature in local, meanwhile the patient claimed severe fatigue and lost self-care ability, regimen of methotrexate plus prednisone was abandoned.
Dynamic change of serum CK-MB levels during the course.
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Due to poor physical condition and severe lung infection, patient was suggested with best supportive care and died of respiratory failure. Dynamic change of serum CK-MB levels during the course were shown in  Figure 4 .