Cutaneous Langerhans cell sarcoma: a case report and review of the literature.

Langerhans cell sarcoma (LCS) is a neoplastic proliferation of Langerhans cells that occurs in lymph nodes, liver, skin, spleen, lung, and bone. We report a case of LCS in a 47-year-old man with a 6-month history of scalp mass and cervical lymphadenopathy. Clinical and pathologic data were available. A histologic examination demonstrated a proliferation of cells with malignant cytologic features. Because of its poorly differentiated morphologic features, hematologic and nonhematologic entities were ruled out by immunohistochemical screening with a broad panel of antibodies. Ultrastructural studies demonstrating Birbeck granules and consistent expression of CD1a, S-100 protein, and langerin by immunohistochemistry were helpful in identifying the Langerhans cell origin.