Hemangioma

What are the main histological types of hemangiomas?

The main histological types of hemangiomas are classified into several groups according to their structure. The following variants are distinguished:

• Capillary (simple, flat, senile) — consists of small capillary-type vessels surrounded by connective tissue.
• Racemose (cirsoid, plexiform) — represented by a tangle of wide and tortuous arterial and venous vessels.
• Cavernous — consists of dilated vascular cavities lined with a single layer of endothelium.
• Mixed — different areas of the tumor exhibit various structural patterns.

Also, a separate classification distinguishes 4 main types: capillary, cavernous, sclerosing hemangiomas, and telangiectasias.

What are the microscopic features of capillary hemangioma?

Microscopically, capillary hemangioma consists of differentiated small capillary-type vessels.

• Vascular structures — densely packed thin-walled capillaries and small cavities filled with blood.
• Endothelium — the cavities are lined with endothelium, and the capillary walls may be formed by markedly swollen (hypertrophic) endothelium.
• Stroma — poorly developed, represented by connective tissue surrounding the vessels.

What are the histological features of cavernous hemangioma?

Histologically, cavernous hemangioma is a vascular lesion built of large, thin-walled caverns.

• Vascular cavities — dilated caverns of various sizes communicating with each other through anastomoses.
• Lining and contents — large thin-walled cavities lined with a single layer of endothelium and filled with blood or thrombotic masses.
• Stroma — the walls of the cavities vary in thickness and are separated by thin stromal layers (connective tissue septa).
• Capsule — the tumor has a fibrous capsule.

Where are cavernous hemangiomas most commonly localized?

Cavernous hemangiomas are most frequently localized in the following areas:

• Skin and mucous membranes — a frequent external localization.
• Internal organs — the liver is affected especially often, where cavernous hemangioma is the most common benign tumor (often located subcapsularly).
• Soft tissues and submucosal layer — also potential sites of development.

In bone tissue, this tumor is extremely rare.

What immunohistochemical markers are used to confirm the endothelial origin of a hemangioma?

For the immunohistochemical study of juvenile hemangiomas, the GLUT-1 marker is used: a positive reaction with the GLUT-1 antibody is noted. In routine hematoxylin and eosin staining during the involution stage, vascular cavities are visualized.

What is the phenomenon of spontaneous regression in juvenile (infantile) hemangioma?

The phenomenon of spontaneous regression (involution) of infantile hemangioma consists of a predictable sequence of its developmental phases.

• Growth phase — in the first weeks and months of life, there is an initial period of rapid growth and an increase in tumor size.
• Stabilization phase — at the age of 1–3 years, tumor growth stops.
• Involution phase — thereafter (usually by age 5), the neoplasm undergoes subsequent slow involution (regression).

As part of which hereditary syndrome do multiple hemangiomas of the cerebellum and retina occur?

Multiple vascular neoplasms of the cerebellum and retina occur as part of von Hippel-Lindau syndrome.

• Hippel-Lindau syndrome — is a hereditary autosomal dominant disorder, one of the manifestations of which is the presence of hemangiomas. Within this syndrome, patients develop multiple hemangioblastomas of the cerebellum and/or spinal cord, as well as retinal angiomatosis.

What fatal complications can cavernous hemangioma of the liver cause?

Cavernous hemangioma of the liver can lead to life-threatening conditions, especially when giant in size.

• Intraperitoneal hemorrhage — occurs as a result of spontaneous rupture of the hemangioma, which is the most dangerous complication.
• Kasabach-Merritt phenomenon — the development of consumption coagulopathy with thrombocytopenia due to platelet sequestration within a giant tumor, which can lead to severe hemorrhagic diathesis.

What is a glomus tumor (glomangioma) and where is it typically located?

A glomus tumor (glomus angioma, Masson tumor) is a benign vascular neoplasm originating from glomus-type arteriovenous anastomoses in the skin (neuromyoarterial receptors involved in thermoregulation). Key characteristics:

• Localization — predominantly the distal phalanges of the fingers and toes, as well as the subungual space.
• Macroscopy — a bluish-red nodule ranging from 0.3 to 1 cm in size.
• Clinical presentation — characterized by pain and potential vasomotor disturbances.

What is the Kasabach-Merritt syndrome in the context of giant vascular tumors?

Kasabach-Merritt syndrome (giant hemangioma with thrombocytopenia) is a severe complication occurring with large capillary or cavernous hemangiomas (more than 5–6 cm in diameter). The pathogenesis of the syndrome is driven by widespread blood clotting (vascular thrombosis) within the tumor itself. This leads to platelet sequestration, consumption coagulopathy, thrombocytopenia, and, consequently, hemorrhagic diathesis accompanied by thrombocytopenic purpura.