Decreased Plasmacytoid Dendritic Cells in Cutaneous Squamous Cell Carcinoma Arising From Subacute Cutaneous Lupus Erythematosus: A Case Report

Patients with cutaneous lupus erythematosus (CLE) are highly susceptible to nonmelanoma skin cancers, including cutaneous squamous cell carcinoma (SCC). Despite the well-established involvement of plasmacytoid dendritic cells (pDCs) in CLE development, the exact role of pDCs in the pathogenesis of CLE-related SCC remains unclear. This report presents a case of SCC arising from a subacute cutaneous lupus erythematosus (SCLE) lesion. Histopathological examination revealed a notable decrease in CD123⁺ pDCs in the SCC lesion compared with that in the SCLE lesion in the same patient. pDCs may exert cytotoxic effects against cancer cells; thus, the absence of pDCs in the microenvironment of cutaneous SCC may facilitate immune evasion by cancer cells, thereby promoting tumor progression. These findings indicate the complex relationship between pDCs and cutaneous SCC development in patients with CLE. Future studies should clarify the role of pDCs in tumor surveillance and progression.