Ki-67 antigen expression and growth pattern of basal cell carcinomas

Abstract

The expression and location of the Ki-67 antigen was investigated in 62 basal cell carcinomas (BCC) using immunostaining techniques (PAP and APAAP) on cryostat sections. The tumor samples were classified into three groups according to microarchitecture (nodular, superficial or fibrosing). The Ki-67 growth fraction displayed great variation between tumors belonging to the same group (nodular type, 7-67%; superficial type, 18-49%; fibrosing type 4-33%). In nodular and superficial BCC formations Ki-67 reactivity was confined either to the nuclei of three to five rows of peripheral cells, or Ki-67-positive nuclei were scattered in the central as well as in the peripheral parts of the tumor strands. The staining patterns varied in an individual tumor. Areas with a high Ki-67 labelling index often occurred adjacent to rather quiescent strands, suggesting that an individual tumor is not in a uniform state of proliferation. So far there are no experimental findings on the regulation of proliferative activity in BCCs. In view of the fact that BCCs are rather slow-growing tumors, the large Ki-67 growth fractions indicate a prolonged duration of the cell cycle or a considerable continuous loss of cells. As the microarchitecture of BCCs is much more complex than would be expected from the location of their Ki-67-positive cells, the growth pattern is probably determined to a high degree by the adjacent connective connective tissue (physical properties and texture of collagen and elastic fibres, enzyme activity of fibroblasts).

Analysis of 1,25-Dihydroxyvitamin D3 Receptors (VDR. in Basal Cell Carcinomas

“…17 It is still unknown what signals determine the extent of proliferative activity in BCCs. 28 Our findings indicate that VDR expression is not exclusively a function of cellular proliferation in these tumor cells, but may be determined by additional, different mechanisms.…”

“…Our findings are in agreement with previous immunohistochemical investigations that have demonstrated peripheral or random distribution of Ki-67-positive cells in BCCs of all different histological types. 28 The actual pro- liferative rate of BCC cells is somewhat unclear, but it appears to be in the range of that of normal keratinocytes. 17 It is still unknown what signals determine the extent of proliferative activity in BCCs.…”

Immunohistochemical evaluation of proliferative activity (Ki-67 index) in different histological types of cutaneous basal cell carcinoma

“…It is not in line with the clinical finding that it is usually a slow-growing and indolent neoplasia with minimal metastatic potential (Tilli et al 2005). This phenomenon could be explained either by a prolonged duration of the cell cycle, or a considerable and continual loss of cells accompanied by their permanent renewal (Baum et al 1993). Already in 1972, Kerr & Searle (1972) supposed that a seemingly paradoxically slow growth rate of BCC might be due to a high apoptotic rate of tumor cells.…”

“…This observation raises the possibility that it may have partly different impact on evolution and biological behavior of this neoplasia. Moreover, the vast majority of the authors (Baum et al 1993;Al-Sader et al 1996;Horlock et al 1997;Lee et al 2000;Tilli et al 2002;Mazzarelli et al 2003;Ionescu et al 2006) found that Ki-67 growth fraction varied considerably between different histomorphological BCC types, even in the tumors belonging to the same group. Our results have shown a wide percentage range in each histological BCC type as well, regardless whether they were primary or recurrent lesions.…”

“…Moreover, BCCs of the skin often manifest a combined morphology consisting of a mixture of several histopathological types, which may contain the cells with different growth potential. Additionally, it is of interest that areas with a high Ki-67 index often occur adjacent to the parts with only sporadical number of Ki-67 positive cells (Baum et al 1993;Tilli et al 2002;Cabral et al 2004). Several authors have noted (Baum et al 1993;Horlock et al 1997;Tilli et al 2002;Cabral et al 2004) that in cutaneous BCCs, Ki-67-labeled cells may be confined either to the few rows of peripheral cancer cells, or they may be diffusely scattered throughout tumor nests.…”