Fine Needle Aspiration Cytology of Langerhans Cell Histiocytosis

Langerhans cell histiocytosis or histiocytosis X is a disease of unknown etiology characterized by proliferation of mature histiocytes. While a few descriptions of the cytologic features of eosinophilic granuloma ocurring in the bone have been published, reports of cytologic findings of lymph node-based Langerhans cell histiocytosis are very rare. We report the cytologic findings of a case of Langerhans cell histiocytosis diagnosed by fine needle aspiration cytology from the left supraclavicular and right inguinal lymph nodes in a 65-year-old male. Cytologic smears showed characteristic reticuloendothelial cells which have elongated, folded, grooved nuclei and abundant pale cytoplasms. Particularly, nuclei were highly irregular and multilobated. A few mitotic figures were present. The cytologic diagnosis was confirmed by tissue biopsies from the left supraclavicular and right inguinal lymph nodes. Proliferation of histiocytes were also present in the skin. Immunohistochemistry for S-100 protein, vimentin, and lysozyme showed positive staining. Electron microscopy disclosed Birbeck granules.