Langerhans cell sarcoma originating from left knee subcutaneous tissue: A case report and literature review.

Langerhans cell sarcoma (LCS) is a neoplastic proliferation of Langerhans cells with notably malignant cytological features. Reports of LCS are sparsely available in English literature; to the best of our knowledge, only 55 cases have been reported. The present study reports a case of LCS originating from subcutaneous tissue of the left knee in a 75-year-old man. The diagnosis of LCS was supported by the results of magnetic resonance imaging, histological and immunohistochemical studies. The tumor began to metastasize to inguinal lymph nodes and eventually involved multiple organs. Chemotherapy and radiotherapy were administered but were ineffective, and the patient died within 2 years of diagnosis. The present case should aid in expanding the currently available knowledge concerning LCS.