Men in red

Abstract

Cutaneous vascular tumours are plentiful and represent one of the most common groups of soft tissue proliferations presenting in the skin. In the majority of cases the histological diagnosis of a cutaneous vascular is straightforward and most lesions are benign. Pathologists face three very challenging tasks when confronted with a skin biopsy containing a vascular proliferation. The first pertains to benign vascular lesions that are often confused with malignancy. This group of lesions includes lesions such as symplastic haemangioma, cutaneous angiomatous nodule, benign lymphangioendothelioma and the atypical vascular lesion arising after radiotherapy amongst others. The second relates to the recognition and accurate diagnosis of low-grade malignant vascular tumours. These tumours are rare and difficult to diagnose and some have been identified recently including pseudomyogenic haemangioendothelioma. The third refers to the accurate diagnosis of poorly differentiated malignant vascular tumours. This task is usually greatly aided by the judicious use of immunohistochemistry including fairly specific vascular markers such as CD31 and the more recently described FLI-1 and particularly ERG. ERG gene fusions occur in subsets of prostatic carcinoma, acute myeloid leukaemia and Ewing sarcoma. ERG is a highly specific marker of endothelial cell differentiation.