title: Intravascular myopericytoma.
abstract: BACKGROUND
  Myopericytoma is a benign tumor composed of cells that show apparent differentiation towards putative perivascular myoid cells called myopericytes. It arises most commonly in the dermis or subcutaneous tissue of the extremities in adults.
  
  
  METHODS
  We describe a myopericytoma that was unusual in its intravascular location.
  
  
  RESULTS
  A 54-year-old man presented with a 10-year history of a painful slowly growing 1.5-cm nodule in the subcutaneous tissue of the thigh. Histologic examination of the excised lesion showed that is was entirely contained within the lumen of a vein. It was composed of a proliferation of myoid-appearing spindle cells, which were arranged in a striking concentric pattern around numerous blood vessels, in a manner that accentuated the vessel walls. This pattern is characteristic of myopericytoma. In some areas, fascicles of spindle cells, embedded in a myxoid stroma, bulged into the lumina of lesional vessels, reminiscent of myofibroma/myofibromatosis. Lesional spindle cells were diffusely positive for smooth muscle actin, focally positive for CD34 and were negative for desmin, cytokeratin, S100 protein, HMB-45 and CD31.
  
  
  CONCLUSIONS
  This case illustrates that myopericytoma can be entirely intravascular in its location.
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis; D006801:Humans; D007124:Immunoenzyme Techniques; D008297:Male; D008875:Middle Aged; D009214:Myoma / Q000737:chemistry / Q000473:pathology* / Q000601:surgery; D009363:Neoplasm Proteins / Q000032:analysis; D009383:Neoplasms, Vascular Tissue / Q000737:chemistry / Q000473:pathology* / Q000601:surgery; D020286:Pericytes / Q000737:chemistry / Q000473:pathology*; D012983:Soft Tissue Neoplasms / Q000737:chemistry / Q000473:pathology* / Q000601:surgery; D040521:Subcutaneous Tissue / Q000737:chemistry / Q000473:pathology / Q000601:surgery
chemical_list: D014408:Biomarkers, Tumor; D009363:Neoplasm Proteins