L1CAM and plexiform neurofibroma: Conversely, L1CAM was downregulated in malignant peripheral nerve sheath tumors compared with plexiform neurofibromas along with other markers of MCs (such as MC chymase, CMA1), hinting at a possible depletion of MCs in this type of malignancy, although L1CAM downregulation was suspected to result from a reduction of Schwann cells by the authors [170].