Benign & malignant neoplasms of vessel walls
Benign vascular tumours:
- Hemangioma
- 7% of all benign tumours of infancy and childhood
- Focussed on head or neck, nearly ⅓ found in liver.
- Variants include capillary (comprised of capillaries), juvenile and cavernous hemangiomas (dilated vascular channels, spaces divided by stroma) as well as pyogenic granulomas (comprised of granulation tissue, often bleed and ulcer).
- Lymphangioma
- Lymphatic counterpart of hemangiomas
- Simple and cavernous form. Simple is found in head and neck, comprised of networks of endothelium lined spaces. Cavernous comprised of massively dilated lymphatic spaces separated by connective tissue stroma.
Malignant neoplasms:
- Angiosarcoma (Hemangiosarcoma)
- Malignant endothelial neoplasms.
- Start small, sharply demarcated asymptomatic red dots, then increase in size and become gray-white masses.
- Microscopic examination shows ranging differentiation, some are clearly endothelial while others are much more generic.
- Hemangiopericytomas
- Derived from pericytes that surround the capillaries. Very rare
- Kaposi sarcoma
- Caused by Kaposi sarcoma herpesvirus, most common in patients with AIDS
- Can be classic, endemic african or transplantation associated
- Has three stages, patch, plaque and nodule lesion.
Kaposi sarcoma, H&E and immunohistochemistry: spindle-shaped endothelial cells infiltrating the dermis between slit-like vascular channels, with haemosiderin, plasma cells, hyaline globules, and HHV8 (KSHV) in the tumour nuclei (brown).
Image: “Histopathology of Kaposi's sarcoma” by Mikael Häggström , M.D. Author info - Reusing images - Conflicts of interest: None Mikael Häggström , M.D. Consent note , CC BY 4.0, via Wikimedia Commons.
Remember: angiosarcoma of the liver is linked to vinyl chloride, arsenic and Thorotrast; angiosarcoma can also arise in skin or breast after radiotherapy, or in an arm with long-standing lymphoedema after mastectomy with axillary node dissection (Stewart–Treves syndrome).