Pathological Model of Hemangioma-New Thinking on Hemangioma Classification.

Sir:

Hemangiomas on the body surface are traditionally classified into strawberry, sponge, mixed, capillary, and racemosum hemangiomas. They were classified into 2 major categories, namely, hemangioma and vascular malformation, by Mulliken and Glowacki[1] in 1982. This was a milestone of progress in the classification of hemangioma. This classification was refined in 1996 and expanded in 2014 by the International Society for the Study of Vascular Anomalies [ISSVA].[2] Vascular tumors were further classified as benign, aggressive, and malignant. However, these classifications are not comprehensive and do not conform to the actual pathology of hemangiomas because hemangiomas are present not only on the body surface but also inside the body. This fact must be taken into consideration when studying the pathology of hemangiomas. In fact, most of the pathological formation of hemangiomas comprises other tissue components, such as fiber, fat, lymph, muscles, bones, nerves, and epithelioids.[3-5] These tissue components can occur in various forms, such as tumor or deformity, hyperplasia or nonhyperplasia, differentiated or undifferentiated, benign or malignant, and different tissue components occur in different proportions, thus forming a huge, complex hemangioma family. The mechanism of occurrence of hemangiomas may be related to pluripotent stem cell or mesenchymal stem cell developmental abnormalities in tumor locations. Therefore, the pathological model of hemangiomas should be composed of 3 parts, namely, vascular tumor, vascular malformation, and other tissue abnormalities, in order to be in concordance with the actual pathology and provide more guidance for the treatment of hemangiomas. Various treatment methods, especially the local drug injection treatment, affect not only the hemangioma and vascular malformations but also other tissues, thereby altering the quality of treatment.

The classification released by ISSVA in 2014 is too complex for the general physicians to master; therefore, most types of hemangioma can be determined eventually only by histological examination. It is necessary to provide a simplified version of the model of hemangiomas at the same time, according to the incidence rate.

Here is an attempt:

The model of hemangioma

Vascular tumor + vascular malformation + other tissue abnormalities

Vascular tumor

Common: infantile hemangioma; rare: invasive, malignant

Malformations

Common: venous, capillary, arteriovenous, lymphatic vessels; rare: mixed

Tumor + malformation + other

Common: mixed hemangioma; rare: various syndromes associated with vascular anomalies

All common types account for more than 90% of all hemangiomas.

DISCLOSURE

The author has no financial interest to declare in relation to the content of this article. The Article Processing Charge was paid for by the author.