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INTRODUCTION

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  • The terms histiocyte and macrophage are synonyms for the mature cell of the monocyte-macrophage system. The latter is the preferred term in discussions of cell biology and immunology, but the former term continues to be used by pathologists and in textbooks for diseases of macrophages because of its entrenchment in the medical literature.

  • A classification of the histiocytoses most relevant to hematologists is shown in Table 37–1. They have been classified based on whether they are monocyte-derived dendritic-cell-related, monocytes-macrophage-related, or neoplastic transformations of dendritic-cells or macrophages.

  • Distinctions among the diseases of macrophages are made based on clinical findings, histopathology, immunophenotyping of surface antigen, cytochemistry, and cytogenetic or genetic features (Table 37–2).

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TABLE 37–1CLASSIFICATION OF HISTIOCYTIC DISORDERS
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Table Graphic Jump Location
TABLE 37–2DISTINCTIONS IN ANTIBODIES TO CELL-SURFACE EPITOPES AND MICROSCOPIC FINDINGS AMONG THE HISTIOCYTIC DISEASES
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CLONAL HISTIOCYTOSES

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Langerhans Cell Histiocytosis

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Definition and History
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  • The term Langerhans cell histiocytosis includes disorders previously called histiocytosis X (eosinophilic granuloma, Letterer-Siwe disease, Hand-Schüller-Christian disease), self-healing histiocytosis, and Langerhans cell granulomatosis.

  • Langerhans cells are macrophages with irregularly shaped nuclei present in epidermis, mucosa, lymph nodes, thymus, and spleen.

  • As all macrophages types, they originate in marrow from a multipotential hematopoietic cell.

  • Identified by unique ...

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