General characteristics and features
The pathology of vascular neoplasms includes two main groups based on their origin: hemangiomas (from blood vessels) and lymphangiomas (from lymphatic vessels).
- The tumors are characterized by slow, expansive growth.
- Approximately 70% of benign forms are congenital in nature.
- There is an ongoing debate in the medical community as to whether these formations are true neoplasms or developmental malformations (hamartomas).
- Malignant variants of vascular neoplasms are classified as sarcomas.
Benign vascular tumors and telangiectasias
Benign hemangiomas are divided into four main types: capillary, cavernous, sclerosing hemangiomas, and telangiectasias.
Telangiectasias are clusters of capillaries, venules, and arterioles, typically localized in the skin and mucous membranes. They can be congenital or acquired (e.g., due to radiation or circulatory insufficiency). A special variant is spider telangiectasias (spider angiomas) with a diameter of 2–5 mm with radial branches, which are frequently found in patients with liver cirrhosis and pregnant women.
Lymphangiomas and glomus tumors
Lymphangiomas are divided into simple (capillary), cavernous, and cystic (hygromas).
- Capillary and cavernous forms resemble hemangiomas but differ by the absence of blood in the cavities and the presence of lymphocytes and lymphoid follicles.
- Cystic lymphangiomas (hygromas) most commonly occur in the neck and axillary region, presenting as multilocular masses filled with clear lymph.
Glomus tumor (Barré-Masson tumor) originates from arteriovenous anastomoses of the glomus type (thermoregulatory receptors). It is localized predominantly on the distal phalanges and in the subungual space, causing marked pain and a bluish-red color of the node.
Tumors of the intermediate and malignant groups
Vascular tumors of the intermediate group have a benign microscopic structure but behave clinically as malignant due to invasive growth:
- Hemangioendothelioma — a variant of capillary tumor consisting of solid masses of proliferating endothelial cells, where only some of the capillaries are functional. Characteristic of young individuals.
- Hemangiopericytoma — a neoplasm originating from capillaries surrounded by clusters of cells derived from pericytes.
Malignant variants of vascular tumors are separated into a distinct category of sarcomas.
Briefly: answers to topical questions
What are the causes of acquired telangiectasias?
The causes of acquired telangiectasias include circulatory insufficiency, Louis-Bar syndrome, and exposure to ionizing radiation. Spider telangiectasias (spider angiomas) occur in patients with liver cirrhosis and occasionally in pregnant women.
What is the microscopic structure of a cavernous hemangioma?
The microscopic structure of a cavernous hemangioma is represented by large dilated vascular spaces (caverns) of varying sizes.
- Vascular spaces — lined by a single layer of endothelium and communicating with each other through anastomoses.
- Cavity contents — filled with blood or thrombotic masses.
- Stroma — represented by thin connective tissue septa (partitions) dividing the caverns.
- Capsule — the tumor has a fibrous capsule.
The walls of the vascular spaces in such a tumor may vary in thickness.
What specific types of malignant vascular tumors are distinguished in the classification?
The classification distinguishes the following specific types of malignant vascular tumors:
- Angiosarcoma — a malignant tumor of blood vessels (code 9120/3).
- Epithelioid hemangioendothelioma, NOS (not otherwise specified, code 9133/3) — includes genetic variants with WWTR1-CAMTA1 fusion and YAP1-TFE3 fusion.
All malignant variants of vascular neoplasms are classified as sarcomas. Meanwhile, Kaposi sarcoma is classified among the intermediate (rarely metastasizing) forms.
How does a capillary hemangioma differ histologically from a cavernous hemangioma?
A capillary hemangioma consists of closely packed, thin-walled differentiated capillaries and small cavities lined by endothelium; its stroma is poorly developed. A cavernous hemangioma consists of large vascular spaces of varying sizes lined by a single layer of endothelium, filled with blood or thrombotic masses, and separated by thin connective tissue septa. In a cavernous hemangioma, the vascular spaces may communicate with each other through anastomoses.
A lymphangioma is like a hemangioma, but without blood: instead, lymph sloshes in the cavities, and lymphoid follicles hide in the tissue.
Class and exam questions
What is the main morphological difference between capillary lymphangiomas and hemangiomas?
In lymphangiomas, erythrocytes and blood are completely absent from the cavities, whereas accumulations of lymphocytes and lymphoid follicles are found in the tissue.
Why is hemangioendothelioma classified in the intermediate group?
Because, despite a relatively benign histological structure, this tumor tends to exhibit invasive, aggressive growth.
Where is the glomus tumor most commonly localized and what is its clinical presentation?
It is localized on the distal phalanges of the hands and feet, especially in the subungual space, and presents as a bluish-red painful nodule.
What else to study on this topic
- Histological findings in sclerosing hemangiomas ( hemosiderin, foreign body giant cells )
- Complications of vascular tumors (ulceration, hemorrhage, infection)
- Structure and microscopy of glomus cells in the Barré-Masson tumor
- Macroscopic appearance of cystic lymphangiomas (hygromas) of the neck region
- Clinical and morphological features of hemangiopericytoma
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