case_images: PMC8023327_01
case_images: Ultrasonography of left forearm before the diagnosis of focal myositis.
case_images: fonc-11-658907-g001.jpg
case_images: PMC8023327_01_fonc-11-658907-g001.jpg
case_images: f1
case_images: 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.
case_images: (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.
case_images: fonc-11-658907-g002.jpg
case_images: PMC8023327_01_fonc-11-658907-g002.jpg
case_images: f2
case_images: Muscle biopsy ( Figures 2A, B  ) showed focal muscle fiber degeneration, increased perimysial cells, and a few inflammatory cells infiltrate around the interstitial blood vessels.
case_images: Protrusion lesion of left elbow.
case_images: fonc-11-658907-g003.jpg
case_images: PMC8023327_01_fonc-11-658907-g003.jpg
case_images: f3
case_images: 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.
case_images: Dynamic change of serum CK-MB levels during the course.
case_images: fonc-11-658907-g004.jpg
case_images: PMC8023327_01_fonc-11-658907-g004.jpg
case_images: f4
case_images: 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 .