Granulomatous slack skin: a clinicopathological and immunohistochemical study of three cases

Three cases of granulomatous slack skin (GSS), a rare variant of T-cell lymphoma, are reported. Immunohistochemical studies using a panel of 16 antibodies were carried out on both frozen tissue and tissue embedded in paraffin wax to characterize the infiltrate. A routine immunoperoxidase technique was used to identify T cells (UCHL1, CD45R0), B cells (L26, 4KB5 [CD45R]), S100 protein-positive cells, monocytes/macrophages (Mac-387, KP1 [CD68]), and dermal dendrocytes (factor XIIIa) in paraffin sections. A close association was found between UCHL1-positive T cells and KP1-positive giant cells. A number of S100-positive cells and factor XIIIa-positive cells were present in the infiltrate from all three patients. The lymphocytes in two of the patients were predominantly of the helper T-cell phenotype. Giant cells from all three patients stained with KP1 (CD68) and Leu M3 (CD14). These studies confirm that the infiltrate in GSS is predominantly a T-cell disorder associated with monocyte-derived cells rather than with resident dendritic macrophages.