Ultrastructural peculiarities in basal cell carcinoma

Abstract

The last decade was marked by a statistically significant increase in the incidence of skin cancers, which motivated the development of new studies to later understand the behavior of these pathologies developing new therapeutic approaches. Also, the multitude of premalignant lesions as well as the complex classification of the carcinomas required a more accurate differentiation of the differential diagnosis, and in this regard the present electron microscopic study contributes significantly. A tumor is a very complex ecosystem represented in particular by (1) genetically modified neoplastic cells and (2) tumor stroma represented by (a) various other cell types (fibroblasts, fibrocytes, mast cells, inflammatory cells, endothelial cells, myelinated or non-myelinated nerves, etc.), and (b) extracellular matrix (basal lamina, elastic fibers and collagen, but also soluble molecules) [1]. The purpose of this study was to discover new aspects of ultrastructure that occur in basal cell carcinoma cases investigated by us, related to the capacity of invasiveness of these tumors. Fresh tumor fragments were obtained with the informed consent of the patients. Here we present some peculiar aspects concerning infrastructure of tumor cells involved in invasive process, especially desmosomal and hemidesmosomal junctions, invadopodia and shedding membrane vesicles. Moreover, here we report about new described cell phenotype termed telocytes involved in cell signaling by their homo- and heterocellular contacts. Telocytes from basal cell carcinoma stroma exhibit a reduced number of heterocellular contacts, which suggests a possible perturbation of tissue homeostasis modulation. Electron microscopic investigations revealed that in invasive basal cell carcinoma intercellular junctions, namely desmosomes are severely altered and that the tumor cells generate and disseminate membrane vesicles, including exosomes inside of the peritumoral stroma. Using transmission electron microscopy to investigate invasive basal cell carcinoma, we have managed to determine the relevance of all these changes for the purpose of evaluation of the invasive capacity of tumor cells within the peritumoral stroma.