Atypical distinctive dermal clear cell mesenchymal neoplasm arising in the scalp

Distinctive dermal clear cell mesenchymal neoplasm (DDCCMN) is a newly described entity characterized by a dermal proliferation of neoplastic cells with clear to reticulated cytoplasm and vesicular nuclei. Atypical features in the form of nuclear pleomorphism and mitoses may be found. The histogenesis of these neoplastic clear cells is not currently known but they are thought to be mesenchymal in origin. Immunohistochemically, they stain positively for NKI-C3 and negatively for melanocytic, epithelial and lymphoid markers. All five cases originally reported by Lazar and Fletcher occurred in the lower extremities. We report herein a case of DDCCMN with atypical features arising in the scalp.