title: [Extracardial rhabdomyoma: a clinicopathologic analysis of 9 cases].
abstract: OBJECTIVE
  To investigate the clinicopathologic characteristics, differential diagnosis and biological behavior of extracardiac rhabdomyoma.
  
  
  METHODS
  Nine cases of extracardiac rhabdomyoma diagnosed between January of 1997 and July of 2014 were reviewed. The clinical, pathologic and immunohistochemical profiles were evaluated.
  
  
  RESULTS
  There were 5 males and 4 females at diagnosis with age ranging from 2 years and three months to 59 years (mean, 37.6 years). Sites included the head and neck region (7 cases), chest (1 case ) and vagina wall (1 case). Clinically, most cases manifested as a subcutaneous nodule or as a submucosal polypoid lesion with a mean diameter of 3.2 cm. Histologically, 4 were adult-type rhabdomyoma characterized by tightly packed large round or polygonal rhabdomyoblasts with abundant eosinophilic to clear cytoplasm; 3 were myxoid variant of fetal rhabdomyoma composed of immature myofibrils, spindled and primitive mesenchymal cells embedded in a myxoid background, 1 was an intermediate form of fetal rhabdomyoma consisting of densely arranged differentiated myoblasts with little myxoid stroma; 1 was a genital rhabdomyoma composed of elongated or strap-like myoblasts scattered in loose fibrous connective tissue. By immunohistochemistry, they showed diffuse and strong positivity for desmin, MSA and myoglobin with variable expression of myogenin. A case of intermediate type also stained for α-smooth muscle actin. Follow up data (2 months ~ 17 years) showed local recurrence in one patient 6 months after surgery.
  
  
  CONCLUSIONS
  Rhabdomyoma is a distinctively rare benign mesenchymal tumor showing skeletal muscle differentiation, which may occassionally recur if incompletely excised. Familiarity with its clinical and morphological variants is essential to avoid misdiagnosing this benign lesion as embryonal rhabdomyosarcoma.
authors.affiliation: Department of Pathology, First People's Hospital, Zhenjiang 212001, China.
authors.forename: Qiuyan
authors.initials: Q
authors.lastname: Sun
authors.affiliation: Department of Oral Pathology, Shanghai Cancer Center, Fudan University, Shanghai 200032, China.
authors.forename: I Weng
authors.initials: IW
authors.lastname: Lao
authors.forename: Lin
authors.initials: L
authors.lastname: Yu
authors.affiliation: Department of Oral Pathology, Ninth People's Hospital, School of Medicine, Shanghai Jiaotong University, E-mail: lijiang182000@yahoo.com.
authors.forename: Jiang
authors.initials: J
authors.lastname: Li
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
mesh_terms: D000293:Adolescent; D000328:Adult; D002454:Cell Differentiation; D002648:Child; D002675:Child, Preschool; D003893:Desmin / Q000032:analysis; D003937:Diagnosis, Differential; D005260:Female; D006258:Head and Neck Neoplasms / Q000737:chemistry / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008637:Mesenchymoma / Q000473:pathology; D008875:Middle Aged; D018008:Myogenin / Q000032:analysis; D009364:Neoplasm Recurrence, Local; D012207:Rhabdomyoma / Q000737:chemistry / Q000473:pathology*; D018233:Rhabdomyosarcoma, Embryonal / Q000473:pathology; D013899:Thoracic Neoplasms / Q000737:chemistry / Q000473:pathology*; D035441:Thoracic Wall / Q000473:pathology*; D014625:Vaginal Neoplasms / Q000737:chemistry / Q000473:pathology*
chemical_list: D003893:Desmin; D018008:Myogenin