A distinctive cutaneous malignant neoplasm expressing the langerhans cell phenotype. Synchronous occurrence with B-chronic lymphocytic leukemia

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Abstract
The authors describe a 63‐year‐old woman who developed a histologically distinctive malignant cutaneous neoplasm composed of large pleomorphic cells with abundant cytoplasm and multilobate, often clefted nuclei that occasionally contained small nucleoli. This neoplastic cell population metastasized to a regional lymph node already involved by a B‐cell derived chronic lymphocytic leukemia expressing surface IgM, BA‐1, and OKT1. The large metastatic tumor cells lacked surface immunoglobulin, B‐lymphocyte associated antigen BA‐1, T‐lymphocyte associated antigens OKT1 and OKT3, and the monocyte/macrophage markers lysozyme and α1‐antichymotrypsin. These tumor cells expressed HLA‐DR antigens, adenosine triphosphatase (ATPase), OKT6, and contained S‐100 protein, i.e., they expressed the phenotype peculiar to epidermal Langerhans cells. The typical clinical and histologic features of Histiocytosis X were absent. Thus, this case appears to represent a distinctive cutaneous neoplasm composed entirely of malignant cells of dendritic cell origin which, by immunophenotypic and histochemical analysis, appear to be related to epidermal Langerhans cells.