Proliferative Myositis: A Comprehensive Review of 33 Case Reports

• Main Authors: Pannawat Trerattanavong, Chinnawut Suriyonplengsaeng, Jariya Waisayarat, ปัณณวัฒน์ ตรีรัตนวงศ์, ชินวุฒิ สุริยนเปล่งแสง, จริยา ไวศยารัทธ์
• Other Authors: Mahidol University. Faculty of Science. Department of Anatomy
• Format: Review Article
• Language: English
• Published: 2022
• Subjects: Proliferative myositis; Pseudosarcomatous tumor; Spindle-like fibroblast/myofibroblast; Giant ganglion-like cell; Immunohistochemistry; โพรลิเฟอเรทีพมัยโอไซติส; เนื้องอกชนิดซาร์โคมาเทียม; เซลล์ไฟโบรบลาสท์/ ไมโอไฟโบรบลาสท์ซึ่งมีรูปร่างคล้ายกระสวย; เซลล์ขนาดใหญ่ที่มีลักษณะคล้ายเซลล์ประสาท; การตรวจทางอิมมูโนฮิสโตเคมี
• Online Access: https://repository.li.mahidol.ac.th/handle/123456789/72909
• Institution: Mahidol University

Proliferative myositis, a rare reactive intramuscular myofibroblastic proliferation, is not well recognized in clinical practice. It overgrows within a few weeks and expands the space between the muscle causing infiltrative-like border mimicking sarcoma. Knowledge of the natural history and pathology of proliferative myositis is essential in order to prevent misdiagnosis and unnecessary surgical resection. Thirty-three reported cases of proliferative myositis in PubMed and Web of Science databases from 2000 to 2018 had been reviewed with the main emphasis in clinical presentation, radiological and pathological findings, treatment, and prognosis. Both males (19 cases) and females (14 cases), predominantly the middle-aged and senior adults, were affected. Upper extremity and shoulder girdle were commonly involved. The chief complaint varied from either painful or painless mass. The traumatic injury was reported as a significant predisposing factor. The lesion typically proliferated and separated muscle bundle. Ultrasonography of the lesion revealed a characteristic “checkerboard pattern” on transverse view. The definite diagnosis was based on the demonstration of spindle-shaped fibroblast/myofibroblast admixed with giant ganglion-like cells in the biopsy. Immunohistochemistry may be useful diagnostic tool when the histopathology was inconclusive. Misdiagnosis of sarcoma occurred due to its rapid growth and infiltrative-like border. Watchful management without surgery was sufficient because of the potential for spontaneous regression. Thoroughly clinical examination and appropriate investigations, including imaging and histopathology, are crucial.