Abstract
PurposeTo study the peculiarities of vascularization at the stromal–epithelial interface in different types of epithelia and their alterations in precancerous lesions.Materials and methodsPeritumoral tissues of 310 patients, tissues of 180 healthy persons and of 50 human embryos and fetuses were used. Traditional histological as well as immunohistochemical methods have been used.ResultsThe study reveals that the occurrence of blood capillaries in surface squamous epithelium is an ordinary event, both in healthy persons and in peritumoral regions of the patients with squamous cell carcinoma. Glandular epithelial coverings, as well as transitional epithelium, do not contain blood vessels. In squamous epithelium, only basal cells are in contact with the membrane and underlying stroma, the cells of the upper layer receiving nutrients through diffusion. Thus, the cells of squamous epithelium are more vulnerable to blood deficiency, since for instance in the pseudo-multilayered respiratory epithelium each cell is attached directly to the basal membrane and has more ample access to the blood supply. Metaplastic squamous epithelium has a markedly reduced vascularization and seems to be more sensitive to carcinogenic stimuli. High-grade dysplastic squamous epithelium and carcinoma in situ do not contain blood vessels.ConclusionThe process of redistribution of vascular network occurring at the interface of epithelial–stromal frontier plays an important role in maintaining the adequate metabolism of cells including those of epithelial covering. Impairment of this mechanism most probably promotes precancerous alterations.
Highlights
A vast amount of literature is devoted to the investigation of the early stages of malignization, especially of the covering epithelium
The study of the distribution of blood vessels in patients with squamous carcinoma as well as in healthy persons revealed that the normal peritumoral squamous epithelial covering is always vascularized
Our results seem to a certain extent obvious, but their association with the processes of carcinogenesis did not attract much attention probably due to the assumption that some of these structures are rather artifacts, nobody has tried to from whence comes the dynamic changes of blood vessel movement and regular character of these patterns? Coexistence of normal epithelial squamous covering containing blood capillaries and adjacent highgrade dysplasia without blood vessels in the same field of vision cannot be the result of tangential cuts or artifacts
Summary
A vast amount of literature is devoted to the investigation of the early stages of malignization, especially of the covering epithelium. We do not wish to diminish the importance of the abovementioned factors in the etiology of cancer but, as pathologists, we have to acknowledge the existence of serious gaps in our understanding of the pathogenesis of malignant growth. One of the most important environmental factors is vascular microcirculation under normal circumstances as a part of the protective mechanisms in the process of malignization, which unlike the phenomenon of angiogenesis in the stroma of tumors [1, 2] has not yet been investigated. One of the most reasonable questions that arises in the process of assessing different factors responsible for malignization of the cell is: how can we explain the existence of different rates of mutation penetrance, the capacity to eliminate oncogenic viruses from cells and other facts which favor the resistance of cells to carcinogenic stimuli? The latter is probably the result of coaction of the adaptational mechanisms, both of intracellular structural and functional type, and external environmental ones.
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