title: Merkel cell tumour with leiomyosarcomatous differentiation.
abstract: OBJECTIVE
  To report and confirm the identity of tumour cells showing leiomyosarcomatous differentiation in a regional lymph node containing metastatic Merkel cell tumour.
  
  
  RESULTS
  A 79-year-old woman was found to have metastatic Merkel cell tumour within an axillary lymph node 4 months after excision of the primary tumour from the forearm. The lymph node was effaced by tumour identical to that of the primary tumour but there was an additional focus of loose spindle cells. Immunocytochemical staining showed the coexpression of cytokeratin 20, neurofilament and desmin in these sarcomatous cells.
  
  
  CONCLUSIONS
  This, to the best of our knowledge, is the first report of Merkel cell carcinoma showing sarcomatous differentiation, and adds to the expanding morphological spectrum of malignant biphasic tumours.
authors.affiliation: Department of Pathology, Ninewells Hospital and Medical School, Dundee, UK.
authors.forename: L
authors.initials: L
authors.lastname: Cooper
authors.forename: R
authors.initials: R
authors.lastname: Debono
authors.forename: N
authors.initials: N
authors.lastname: Alsanjari
authors.forename: A
authors.initials: A
authors.lastname: Al-Nafussi
mesh_terms: D000368:Aged; D015266:Carcinoma, Merkel Cell / Q000378:metabolism / Q000473:pathology*; D002454:Cell Differentiation; D003893:Desmin / Q000032:analysis; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007381:Intermediate Filament Proteins / Q000032:analysis; D053554:Keratin-20; D007890:Leiomyosarcoma / Q000378:metabolism / Q000473:pathology*; D008198:Lymph Nodes / Q000737:chemistry / Q000473:pathology; D008207:Lymphatic Metastasis; D016900:Neurofilament Proteins / Q000032:analysis; D012878:Skin Neoplasms / Q000378:metabolism / Q000473:pathology*
chemical_list: D003893:Desmin; D007381:Intermediate Filament Proteins; C507499:KRT20 protein, human; D053554:Keratin-20; D016900:Neurofilament Proteins