title: Primary cutaneous rhabdomyosarcoma: a clinicopathologic review of 11 cases.
abstract: BACKGROUND
  Rhabdomyosarcoma is a malignant mesenchymal tumor with skeletal muscle differentiation. Primary cutaneous rhabdomyosarcoma is rare. We report a series of 11 cases of primary cutaneous rhabdomyosarcoma.
  
  
  METHODS
  Cases diagnosed as rhabdomyosarcoma arising in the dermis/subcutis with no identified primary tumor elsewhere were retrospectively reviewed. Follow-up was obtained.
  
  
  RESULTS
  The tumors occurred in five children and six adults. The adult subset consisted of pleomorphic, epithelioid and not otherwise specified (NOS) subtypes while the pediatric subset showed alveolar and embryonal subtypes. All cases showed immunohistochemical staining consistent with the diagnosis of rhabdomyosarcoma. Three adult cases showed immunoreactivity for cytokeratins (one pleomorphic, one epithelioid and one NOS.
  
  
  CONCLUSIONS
  Primary cutaneous rhabdomyosarcoma shows a bimodal age distribution and male predominance, correlating with rhabdomyosarcoma in deep soft tissue. Follow-up, available on all patients, showed aggressive behavior in both children and adults. Primary cutaneous rhabdomyosarcoma should be considered in the differential diagnosis of tumors with abundant eosinophilic cytoplasm and those with "small round blue cell" morphology. Desmin, myogenin and MYOD1 are a trio of markers with high sensitivity and specificity for primary cutaneous rhabdomyosarcoma. Cytokeratin immunoreactivity in primary cutaneous rhabdomyosarcoma represents a potential diagnostic pitfall in the differential diagnosis with sarcomatoid carcinoma.
authors.affiliation: Department of Anatomic Pathology, Cleveland Clinic, Cleveland, OH, USA.
authors.forename: Trent B
authors.initials: TB
authors.lastname: Marburger
authors.forename: Jerad M
authors.initials: JM
authors.lastname: Gardner
authors.forename: Victor G
authors.initials: VG
authors.lastname: Prieto
authors.forename: Steven D
authors.initials: SD
authors.lastname: Billings
mesh_terms: D000293:Adolescent; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000378:metabolism*; D002675:Child, Preschool; D003593:Cytoplasm / Q000378:metabolism / Q000473:pathology; D020405:Dermis / Q000378:metabolism / Q000473:pathology; D003937:Diagnosis, Differential; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D007633:Keratins / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D017570:MyoD Protein / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000378:metabolism*; D012189:Retrospective Studies; D012208:Rhabdomyosarcoma / Q000378:metabolism / Q000473:pathology; D012737:Sex Factors; D012878:Skin Neoplasms / Q000378:metabolism / Q000473:pathology
chemical_list: D014408:Biomarkers, Tumor; D017570:MyoD Protein; C057363:MyoD1 myogenic differentiation protein; D009363:Neoplasm Proteins; D007633:Keratins