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We investigated the co-distribution of lymphocyte subpopulations and non-lymphoid 'accessory' cells in 35 cases of cutaneous lymphoproliferative diseases (T-cell lymphoma, 10 cases; B-cell lymphoma, 17 cases; pseudolymphoma, 8 cases) using immunohistochemical methods. T-zone histiocytes and particularly Langerhans cells were abundant in all cutaneous T-cell lymphomas, but were also found in B-cell lymphomas. T-zone histiocytes were associated with T-lymphocytes, especially T-helper cells, but not with T-suppressor cells. Dendritic reticulum cells were essentially confined to well differentiated germinal centres. Macrophages occurred in both lymphomas and pseudolymphomas without definite relationship with either B- or T-cells. In malignant lymphomas of high grade malignancy, macrophages represented the only non-lymphoid cell type. Our results indicate that malignant lymphoid cells, like normal lymphocytes, require definite micro-environments which are, at least in part, maintained by certain non-lymphoid cells.

Germinal center cell-derived (GCC) malignant lymphomas are B-cell tumors that represent neoplastic equivalents of normal lymphoid follicles. These lymphomas include, in the Kiel classification, three main types: centrocytic lymphoma, centroblastic-centrocytic lymphoma, and centroblastic lymphoma. We have diagnosed 13 cases of germinal center cell-derived cutaneous lymphomas among 178 evaluated malignant lymphomas of the skin. Some clinical, histologic, and immunologic aspects are discussed in this article.