L1CAM and histiocytic neoplasm: Moreover, we investigated the expression of L1CAM in a series of 12 cases of mesenchymal and rare histiocytic neoplasms/proliferations, including four cases of histiocytic sarcoma, two cases of Rosai–Dorfman disease, one Langerhans cell histiocytosis, three cases of liposarcoma (including de‐differentiated and inflammatory liposarcoma) and one monophasic synovial sarcoma, as well as one tumour with features between an indeterminate dendritic cell tumour and a Langerhans cell sarcoma.