Case Six – June 2017
- 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
- Angioma
- Nevus
- Metastatic breast cancer
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.
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
- 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