Langerhans cell sarcoma (LCS) is a neoplastic proliferation of Langerhans cells with overtly malignant cytological features and is considered a higher-grade variant of Langerhans cell histiocytosis (LCH). In 2001, the World Health Organization (WHO) categorized malignant neoplasms derived from Langerhans cells into two categories: LCH and LCS. LCS is principally diagnosed by histopathological findings. There have only been 27 LCS cases reported thus far. LCS originating from the skin is rare; only 10 cases have been reported. We report a 76-year-old woman who had a plaque on the scalp. Hematoxylin-eosin stained images showed a malignant, pleomorphic component with diffuse proliferation of tumor cells with grooved nuclei, distinct nucleoli, and an abundant cytoplasm from the dermis to the subcutaneous layer. An immunohistochemical study revealed positive CD1a, langerin, and S-100 protein staining. While the MIB-1 index was high (90%), mitosis was 20/10 under a high-power field, which does not fulfill the WHO 2008 criteria (criterion is >50/10 under a highpower field). However, we considered that our case was not LCH, but LCS, because of the distinction of LCH is in the clinical appearance, which differed from previous cases described in textbooks. Utilizing a comparative review of the clinical appearance 10 examples of LCS occurring from the skin reported thus far, we compared them with our case. With regard to the site of occurrence, four of seven cases were found in the extremities, two cases were found in the abdomen, and one in the scalp. The lesions were mostly solitary tumors or plaques, in contrast to LCH, which mostly consists of multi-centered eczematous or papular lesions.
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