An immunohistochemical analysis of lymphocytic infiltrations in canine skin cancers

Abstract

Lymphocytic infiltrations located in the extracellular matrix often accompany canine skin cancer. They can be characterised as an inflammatory infiltration and/or a second tumour - lymphoma. The aim of this study was an immunohistochemical analysis of a lymphocytic infiltration which accompanies spontaneous skin cancer. Twenty basal cell carcinoma, 20 non-keratinizing squamous cell carcinoma, 20 keratinizing squamous cell carcinoma and 8 sebaceous gland carcinoma samples which were accompanied by a lymphocytic infiltration and/or secondary lymphatic follicles were verified histopathologically. The expression of bcl-2, CD3, CD79α, Ki-67, MCM-3 and MCM-7 in the lymphocytic infiltration was evaluated. Four types of lymphocytic infiltrations were found: I - diffuse bcl-2+, II - diffuse bcl-2-, III - follicular bcl-2+/- where the centre was bcl-2-, and the marginal zone of the follicles and the extrafollicular area were bcl-2+ and IV - aggregated bcl-2+, where the centre and periphery were bcl-2+. The I and IV type corresponds to lymphoma, II type is non-neoplastic immune response and III type suggest reactive follicular hyperplasia. The proliferation of lymphocytes which demonstrated the expression of neoplastic markers (I and IV), suggests preneoplastic phase (pseudolymphoma) or lymphoma - the second independent tumour. A high proliferative index of the follicular blc-2+/- follicular infiltration indicates an increased immunological response of the host against skin cancer.