Atypical vascular lesion
AVL; benign lymphangiomatous papules; post-radiation atypical vascular proliferation
Atypical vascular lesions are small, benign-behaving but histologically alarming vascular proliferations that arise within fields of previous radiotherapy — most commonly the breast skin years after adjuvant radiotherapy for breast cancer. Two histological patterns are recognised: lymphatic-type (commonest) and vascular-type. While they are themselves benign, AVLs share a clinical and histological continuum with post-radiation cutaneous angiosarcoma, and a small proportion progress to angiosarcoma over time. MYC immunohistochemistry is the single most useful test to distinguish AVL (MYC-negative) from post-radiation angiosarcoma (MYC-amplified, MYC-positive). Local excision of all suspicious lesions and surveillance of the irradiated field are the cornerstones of management.
Clinical features
- Small (3–10 mm), red-violaceous or skin-coloured papules or vesicle-like lesions in a previously irradiated field.
- Most commonly in the breast skin or chest wall after adjuvant radiotherapy for breast cancer; latency typically 3–10 years.
- May be solitary or multiple; some patients have dozens.
- Asymptomatic or mildly itchy.
- Differential: post-radiation angiosarcoma, telangiectasia, lymphangioma circumscriptum, Kaposi sarcoma.
Histology & subtypes
- Lymphatic-type AVL (commonest) — dilated, thin-walled vascular spaces in the superficial dermis lined by bland endothelial cells, sometimes with focal atypia. Intraluminal projections may be present.
- Vascular-type AVL — well-formed irregular vascular channels in the superficial / mid dermis, sometimes with focal atypia.
- No tumour necrosis, no significant mitoses, no infiltrative deep extension.
- Endothelial markers positive (CD31, CD34, ERG); D2-40 positive in lymphatic-type.
- MYC IHC negative — the critical distinction from post-radiation angiosarcoma, which is MYC-amplified and MYC-positive on IHC in the majority of cases.
- FISH for MYC amplification can be used in equivocal cases.
Management
- Excisional biopsy of any suspicious lesion to obtain definitive histology and MYC status.
- Wide local excision with histological clearance for confirmed AVL — recurrence at the same site is common.
- Surveillance of the entire irradiated field — clinical examination every 6 months for at least 5 years; longer in patients with multiple AVLs.
- Patient education to flag any new lesion in the radiation field promptly.
- Mapping biopsies of suspicious areas may be needed to delineate field disease prior to surgery.
- If MYC-positive on IHC or imaging suggests deep extension — manage as post-radiation angiosarcoma.
Prognosis
AVL itself is benign, but it is a marker of an irradiated field at risk for angiosarcoma. The reported rate of progression to (or co-existence with) post-radiation angiosarcoma in patients with AVLs is variable but well-documented, and any rapidly growing, ulcerating or violaceous nodule in a known AVL field warrants urgent biopsy with MYC assessment. Long-term surveillance is essential.
References
- Patton KT et al. Atypical vascular lesions after surgery and radiation of the breast. Am J Surg Pathol; 2008.
- Mentzel T et al. Postradiation cutaneous angiosarcoma after treatment of breast carcinoma is characterized by MYC amplification. Mod Pathol; 2012.
Spot a correction?
If any clinical statement, citation or link on this page needs updating, please email admin@skinoncology.net with the page name, the proposed correction and the supporting source.