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, CD45RO), 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.