Differential immunophenotypic analysis of dendritic cell tumours.

Aims: The phenotypic and biological characteristics of dendritic cell (DC) tumours have not been fully elucidated. The aim of this study was to compare the immunophenotypic characteristics of DC-related markers and cell-cycle-associated markers among DC tumours and finally to utilise them for differential diagnosis of DC tumours.

Methods: Tissue sections from 28 patients with DC tumours were immunohistochemically examined using DC-related and cell-cycle-associated markers.

Results: The Langerhans cell histiocytosis (LCH) and Langerhans cell sarcoma (LCS) samples were positive for S-100 protein, CD1a, Langerin, fascin, DEC-205 and DC-SIGN. Interdigitating dendritic cell sarcoma (IDCS) was positive for S-100 protein and fascin and negative for Langerin. In addition, two IDCS samples were positive for CD1a, DEC-205 and DC-SIGN. The labelling indices of Ki-67, cyclin A, cyclin B1 and acetylated histone H3 on the LCS and IDCS specimens were significantly higher than those on the LCH specimens. The expression of p53 was also significantly higher in the LCS specimens than in the LCH specimens. The numbers of infiltrating CD123(+) and FOXP3(+) cells were also significantly higher in the LCS samples than in the LCH and IDCS samples. Follicular dendritic cell sarcoma was distinguished from other DC tumours by the lack of DC-SIGN, Langerin and DCE-205.

Conclusions: These results suggest that Langerin can be used to distinguish LCS from IDCS, and DC-SIGN and DEC-205 can be used to identify DC tumour cells. The frequency of cell-cycle-associated markers can be used for the differential diagnosis of malignant and benign DC tumours.