Background: Expression of CD30 antigen is a distinct marker of lymphocyte activation that was originally described in the Reed–Sternberg cells of Hodgkin's disease. The observation of CD30+ cells has been considered a diagnostic feature of cutaneous CD30 lymphoid proliferations. However, CD30 expression has also been reported in some cutaneous benign inflammatory infiltrates.
Methods: Eleven skin biopsies from patients with scabies were double-blindly and retrospectively analysed. A panel of histopathological parameters and immunophenotypic expression of CD4, CD8, CD30 and S-100 antigens was studied. CD30 and S-100 antigens expression were related to clinical features.
Results: Large CD30+ cells were demonstrated in eight (8/11) biopsies, corresponding to patients with long-standing lesions (3 months or longer). However, no expression of the CD30 antigen was observed in all biopsy specimens (3/11) corresponding to early lesions (2 months or less). The presence of S-100 positive cells in the papillary dermis was an almost constant feature.
Conclusions: CD30+ large cells seem to be a common feature in long-standing infiltrates of scabies. CD30 expression in scattered cells of a cutaneous lymphoid infiltrate cannot be assessed as a strong diagnostic argument of neoplastic cutaneous CD30+ lymphoid proliferation (lymphomatoid papulosis/cutaneous CD30+ lymphoma). Therefore, the possibility that large atypical CD30+ cells may be also present in several benign inflammatory diseases should be always considered.