Update on cutaneous epithelioid vascular tumours

Cutaneous epitheiloid vascular tumours are heterogeneous groups of vascular proliferations sharing in common the epithelioid morphology of tumour cells. Based on the WHO classification epithelioid vascular tumours are classified on the basis of their biological behavior into benign tumours (epithelioid haemangioma, epithelioid angiomatous nodule) and malignant tumours (epithelioid haemangioendothelioma and epithelioid angiosarcoma). While cutaneous epithelioid haemangioendothelioma affecting only the skin usually but not always follows an indolent clinical course, cutaneous epithelioid angiosarcoma is generally a highly aggressive tumour with dismal prognosis. Also included in this review is pseudomyogenic haemangioendothelioma, a vascular tumour of intermediate (rarely metastasizing) malignancy. It is not traditionally grouped under vascular tumours with epithelioid morphology. Nevertheless, pseudomyogenic haemangioendothelioma is discussed herein because it often contains a proportion of cells with epithelioid morphology, mimicking other epithelioid tumours of different lineage. Correct recognition of cutaneous epithelioid vascular tumours can be difficult due to their overlapping histological features and often absent or limited formation of open vascular spaces, but is crucial for correct management of the patients. In this paper, we review the main clinicopathological and immunohistochemical features of cutaneous epithelioid vascular tumours, including pseudomyogenic haemangioendothelioma, discuss their crucial differential diagnosis, analyze treatment options and prognosis, and give an update on molecular genetic features of this distinctive group of vascular proliferations.