en تخصصي Special گزارش مورد case report <span style="font-size:14px;"><span style="font-family:times new roman;"><span style="color:#008080;"><strong><em>Background: </em></strong></span>Anaerobic, nonsporulating, Gram-positive bacteria groups called actinomyces organisms are responsible for the so called actinomycosis. This chronic disease is rare in children and has tendency to mimic many other diseases. It also has wide variety of manifestations and non-specific symptoms. As a result, it is difficult to diagnose before the biopsy and microscopic examination. Although infection may involve any organ in the body, the significant sites of actinomyces infection include cervicofacial, abdominal, pelvic and pulmonary tissues.<br> <span style="color:#008080;"><strong><em>Case report:</em></strong></span> Here, we describe one case of unusual presentation; an 11-year-old girl with a soft tissue mass in the left lower lateral chest wall which was finally diagnosed actinomycosis based on the pathological findings.<br> <span style="color:#008080;"><strong><em>Conclusions:</em></strong></span> Actinomycosis may rarely present with chest wall mass.</span></span> Actinomyces, Child, Microscopic Examination, Soft Tissue 358 361 http://caspianjp.ir/browse.php?a_code=A-10-78-4&slc_lang=en&sid=1 Ahmad Tamaddoni drtamaddoni@yahoo.com 10031947532846002724 10031947532846002724 Yes Associated Professor of Pediatrics Hematology and Oncology, Non-Communicable Pediatric Diseases Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, IR Iran. Sedighe Norouzian norouzian88s@gmail.com 10031947532846002725 10031947532846002725 No Resident of Pediatrics, Student Research Committee, Babol University of Medical Sciences, Babol, Iran. Ali Mohammadpour Mir alimmir41@gmail.com 10031947532846002726 10031947532846002726 No The Clinical Research Development Unit of Amirkola Children's Hospital, Babol University of Medical Sciences, Babol, IR Iran. Seyedmohamadreza Tabatabaie m.tabatabaie_dr@yahoo.com 10031947532846002727 10031947532846002727 No The Clinical Research Development Unit of Amirkola Children's Hospital, Babol University of Medical Sciences, Babol, IR Iran.