Case Six – June 2017

  • Patient Information
    • 30 year old female presented with a new 1 cm pink, papule overlying the axillary tail of the breast
    • She has a history of radiation therapy for breast cancer approximately 8 years ago

  • Clinical Diagnosis
    • Angioma
    • Nevus
    • Metastatic breast cancer
  • Histology

    Sections show a diffuse proliferation of variably-sized, ectatic and irregularly branching vessels throughout the dermis.

    High power examination shows the vascular spaces are lined by a single layer of endothelial cells. Small intraluminal papillary projections and hobnailing of the endothelial cells are seen. No significant cytologic atypia is present.  HHV-8 immunohistochemical stain is negative.

  • Final Diagnosis

    Atypical vascular lesion

     

    • Atypical vascular lesion, AVL, represents a benign postradiation vascular proliferation
    • AVL can be classified histologically into two categories: lymphatic and capillary vascular type
    • The main histologic differential diagnosis includes angiosarcoma arising in the setting of prior radiation therapy
    • AVL are often <1 cm in size, circumscribed, limited to the dermis and contain no significant cytologic atypia or multilayering of endothelial cells
    • In contrast, angiosarcomas average 7 cm in size, may extend into the subcutaneous tissue, and show multilayered, atypical tumor cells with prominent nucleoli
    • Both AVL and angiosarcomas can be multifocal
    • Postradiation angiosarcoma often shows amplification of the MYC oncogene using immunohistochemical or FISH techniques
      • AVL does not show MYC amplification
    • The clinical behavior of atypical vascular lesions is not entirely known
      • Approximately 10-20% of patients with AVL will develop multiple lesions
      • A subset of AVL may progress to angiosarcoma
      • This progression may be more frequently associated with the capillary vascular type and in any AVL with nuclear atypia
    • Most AVL patients have a favorable clinical course following complete excision
  • Summary
    • Atypical vascular lesion, AVL, represents a benign postradiation vascular proliferation which mimics angiosarcoma clinically and histologically
    • AVLs are often <1 cm in size, circumscribed, limited to the dermis and contain no significant cytologic atypia or multilayering of endothelial cells
    • In contrast, angiosarcomas average 7 cm in size, can extend into the subcutaneous tissue, and show multilayered, atypical tumor cells with prominent nucleoli
    • The clinical behavior of atypical vascular lesions is not entirely known, and some believe a subset of AVL may progress to angiosarcoma
    • Most AVL patients have a favorable clinical course following complete excision