Langerhans cell sarcoma (LCS) is an extremely rare malignant dendritic cell neoplasm with Langerhans cell differentiation. Conventional cytology, based on cell morphology alone, cannot render a cytological diagnosis of LCS because immunochemical analysis is essential to identify the Langerhans cell immunophenotype. We present a case illustrating the value of liquid-based cytology with immunocytochemistry as compared with conventional cytology, along with histological and immunohistochemical findings. A 92-year-old woman presented with a 1-month history of progressive right cervical lymphadenopathy. Cytology of a fine needle aspiration sample from the right superior internal jugular lymph node revealed proliferation of atypical, pleomorphic, and histiocytoid cells with one or more irregular-shaped nuclei. Compared with conventional cytology, liquid-based cytology demonstrated more clustered and spatial cells, slightly less marked nuclear atypia, more intense light green staining of the cytoplasm, and a clearer background. Immunocytochemical analysis of the abnormal cells revealed expression of vimentin, CD1a, langerin, CD68, and S-100. The combined morphologic and immunocytochemical results strongly indicated LCS. Histological and immunohistochemical examination of a subsequent excisional biopsy specimen closely coincided with the results of liquid-based cytology. Thus, this technique, including the use of immunocytochemistry, is very useful and valuable for the pathological diagnosis of nonepithelial and hematopoietic neoplasms. There are subtle but considerable differences in cell morphology between conventional and liquid-based cytology; these differences include clusterability, spatial findings, dyeability, and atypism as illustrated in this case of LCS.
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