Clinical and immunohistochemical evaluation of the vulvar Langerhans cell histiocytosis

We present the case of a woman with diabetes insipidus with subsequent genital and multiorgan Langerhans cell histiocytosis (LCH). A monolateral and slightly infiltrated erythematous plaque of the vulva was observed. Hematoxylin and eosin and immunophenotypic studies were performed. The primary antibodies used were monoclonal antibody to S100, CD1a, CD34, HLA-DR, PCNA, CD45Ro, CD40, and langerin. The histology of the infiltrates revealed a granulomatous reaction pattern, with extensive aggregates of histiocyte proliferation. The histiocytes, morphologically characterized by a pale staining of cytoplasm surrounding a grooved reniform nucleus, sometimes contained small distinct nucleoli. Lymphocytes, eosinophils, macrophages, and both plasma cells and giant cells typically infiltrated the lesions. Cells CD1a+ and S100+ infiltrated the epidermic and were dispersed over the infiltrates as well as in clusters, and around the vessels. A considerable number of CD40-expressing cells were restricted to CD1a+ LCH cells. The specimen contained a high percentage of langerin+ cells in both the dermis and the epidermis. The clinical manifestations of LCH affecting the genital area can be diverse, and in most patients take the form of ulcers or erythematous plaques. Histopathologic examination of the lesion evidences a mixture of Langerhans cell histiocytes (CD1a+, S100+, HLADr+, CD207+, CD 40+), lymphocytes (predominantly helper [CD4] CD 45 Ro+), eosinophils, and macrophages. Each of the cell types produces a "cytokine storm." Many of the cytokines favor recruitment of Langerhans cell progenitors and rescue the Langerhans cell histiocytes from apoptosis.