Malignant Clear Cell Acanthoma: Report of a Rare Case of Clear Cell Acanthoma-Like Tumor With Malignant Features.

An erythematous and moist tumor nodule on the left temple of a 92-year-old woman was biopsied and identified as a clear cell acanthoma (CCA)-like tumor with malignant cytology and high proliferation activity. This case is similar to 2 cases reported previously as atypical CCA. The authors believe that these tumors are malignant counterparts of CCA and propose to call them malignant CCA. The clinicopathologic features of the present case are described along with dermoscopic findings.