A neoplastic proliferation of Langerhans cells with overtly malignant cytologic features. It can be considered a higher grade variant of Langerhans cell histiocytosis (LCH) and it can present de novo or progress from antecedent LCH. (WHO, 2001). The disease is Langerhans cell sarcoma (MONDO_0019480, a Monarch Disease Ontology identifier). Also known as: sarcoma of Langerhans cell.