Lethal Non-Langerhans Cell Histiocytoses: Necrobiotic Xanthogranuloma and Xanthoma Disseminatum

Abstract

The histiocytic disorders encompass a broad range of malignant and nonmalignant entities capable of presenting in a variety of clinical and pathologic guises. The histiocytic disorders are generally classified by the cell of the origin, and specifically as bone marrow tissue-derived monocytes that migrate secondarily to the skin serving as either phagocytic macrophages or antigen-presenting dendritic or Langerhans cells. Langerhans cells typically reside closely to the epithelium and traffic to the lymph nodes. They are important in immunologic surveillance and are defined by the presence of Birbeck granules on ultrastructural examination, as well as S-100 and CD-1a immunopositivity. This discussion will focus upon the entities comprised of the phagocytic non-Langerhans cell macrophages and specifically the disorders within this category capable of producing or being associated with significant morbidity or mortality.