Abstract
Purpose:
Basal cell carcinoma (BCC) is a locally invasive tumor which can be subdivided in a fairly benign solid variant and a more aggressive fibrosing type. Since in oncology there is increasing evidence for the importance of macrophages (Ms) interacting between tumor cells and their surroundings, thereby affecting not only the infiltrative potential but also the patients' prognosis, we wanted to compare these two BCC variants regarding the presence and localisation of tumor-associated Ms.
Methods:
We studied 15 specimens of solid BCC (BI) and 15 of fibrosing BCC (BII). Mean age in both groups was similar (73 vs.75 years). Fibrosing BCC was located almost exclusively in the lower eyelid while solid BCC was located more diversely around the eye. H&E sections were evaluated for the presence of associated inflammation (score + to +++). Immunohistochemistry was performed with antibodies against CD68 (Dako;1:100), CD163 (EnzoLifeSciences;1:100) and Ki67 (Dako;1:100). Positive reacting cells were visualized either using AEC or immunofluorescence and counted in a standard fashion and/or by means of Automatic Nuclei Counter plug-in for ImageJ. Evaluation was performed by at least 2 different readers, and IBM SPSS 20 was used for statistical analysis.
Results:
In all specimens, an inflammatory component was observed which - as judged by H&E - was significantly more pronounced in BII compared to BI (p<0.001). Ms were also more frequent in BII (p<0,05), however, no significant difference in M subtype was found between both groups. In both BI and BII, Ms were much more frequent in the surrounding stroma compared to the tumor itself (p<0.001). Ms within the tumor were more frequent in BII compared to BI (p<0,05), and in both groups those Ms always belonged to the M1(CD68+CD163-) category. Ki67 index was similar in both groups.
Conclusions:
Fibrosing BCC, more likely to be located at the lower eyelid, is associated with a significantly more intense inflammatory reaction in the surrounding tissue. From our data, however, there was no significant difference in the subtype of Ms when comparing both groups. Thus, in BCC, macrophage polarization does not seem to be particularly relevant regarding infiltrative growth, and tumor-associated chemokines attracting/stimulating inflammatory cells other than Ms might also be important in tissue destruction and thereby invasive potential. It remains unclear whether localisation of the tumor plays a major role in this.