March 2004

2.

Histopathology: Revealed a well-circumscribed lesion composed of atypical vessels with a dissecting growth pattern, limited to the superficial dermis. The vessel spaces are lined with inconspicuous endothelial cells with mild cytologic atypia.

Diagnosis: Atypical Vascular Proliferation [AVP]

The histologic description of this lesion, a well-circumscribed neoplasm composed of atypical vessels with a dissecting growth pattern and limited to the superficial dermis, with vessel spaces lined with inconspicuous endothelial cells, is consistent with an atypical vascular proliferation.

This lesion has been described in women previously treated with radiation therapy for breast carcinoma.1-4 It typically presents as a discrete pink papule 3-4 mm in size, occurring on the surface of irradiated tissue. They occur most commonly as a single papule, but rarely may also present with multiple papules.

The lesion is referred to as "atypical" because the endothelial cells lining the vessels, although monomorphous and single-layered, may have mild cytologic atypia. In addition, the lesion is often not well circumscribed, and the anastamosing and dissecting pattern of vascular proliferation may be concerning for an aggressive vascular neoplasm.

Although the two may be confused, AVP is distinguished from angiosarcoma by a more innocuous clinical and histopathologic appearance. Features of AVP that distinguish it from angiosarcoma are the lack of involvement of the subcutaneous tissues, the lack of substantial cytologic atypia, and the monomorphous single layer of endothelial cells lining the vascular channels, which lack prominent nucleoli and mitotic figures.

The histopathologic findings of AVP are suggestive of a lymphatic origin.1 The vascular and lymphatic changes of AVP are suspected to be a manifestation of radiation damage to cutaneous tissue. While benign clinically, these lesions are of great importance as they can be clinically and histologically mistaken for angiosarcoma, a malignancy with a consistently aggressive course and poor long-term outcome that is also seen in post-radiation patients.

Treatment consists of simple excision. Long-term follow-up of similar patients, as reported in the literature, has shown that these lesions are not associated with recurrence, aggressive local growth or metastasis. Finally, there is no evidence to suggest that the atypical vascular proliferation represents a precursor to angiosarcoma.

References:

1. C Diaz-Cascajo, S Borghi, W Weyers, H Retzlaff, L Requena, D Metze. Benign lymphangiomatous papules of the skin following radiotherapy: a report of five new cases and a review of the literature. Histopathol. 35:319-327, 1999.

2. A Gottfarstein-Maruani, E Esteve. Benign vascular proliferations in previously irradiated skin. Am J Surg Pathol. 26:1372-1373, 2002.

3. L Requena, H Kutzner, T Mentzel, R Duran, JL Rodriguez-Peralto. Benign vascular proliferations in irradiated skin. Am J Surg Pathol. 26: 328-337, 2002.

4. S Fineberg, PP Rosen. Cutaneous angiosarcoma and atypical vascular lesions of the skin and breast after radiation therapy for breast carcinoma. Am J Clin Pathol. 102: 757-63, 1994.

5. SF Sener, S Milos, JL Feldman, et al. The spectrum of vascular lesions in the mammary skin, including angiosarcoma, after breast conservation treatment for breast cancer. J Am Coll Surg. 193: 22-27, 2001.

Drs. Julie Lowe andMichael Heffernan presented this case.