The Histiocyte Society classification of histiocytoses and neoplasms of macrophage-dendritic cell lineages is currently in its 2016 revision of the organisation's initial classification system from 1987.
Terminology
Histiocytes are mononuclear phagocytes that reside in tissues, including macrophages and dendritic cells. Histiocytoses are disorders characterised by the accumulation of cells derived from macrophages or dendritic cells.
Classification
L (Langerhans) group
- Langerhans cell histiocytosis
- Erdheim-Chester disease
- indeterminate cell histiocytosis
- mixed Langerhans cell histiocytosis and Erdheim-Chester disease
C group: cutaneous and mucocutaneous non-Langerhans cell histiocytoses
- cutaneous non-Langerhans cell histiocytoses
- xanthogranuloma family
- non-xanthogranuloma family
- cutaneous Rosai-Dorfman disease
- necrobiotic xanthogranuloma
- cutaneous histiocytoses not otherwise specified
- cutaneous non-Langerhans cell histiocytoses with a major systemic component
- xanthogranuloma family
- non-xanthogranuloma family
M group: malignant histiocytoses
- primary malignant histiocytoses
- secondary malignant histiocytoses (following or associated with another haematologic neoplasia)
- subtypes
- histiocytic
- interdigitating cell
- Langerhans cell
- indeterminate cell
- not specified
R group: Rosai-Dorfman disease and miscellaneous noncutaneous, non-Langerhans cell histiocytoses
- familial Rosai-Dorfman disease
- sporadic Rosai-Dorfman disease
- classical (nodal) Rosai-Dorfman disease
- extranodal Rosai-Dorfman disease
- neoplasia-associated Rosai-Dorfman disease
- immune disease-associated Rosai-Dorfman disease
- other non-C non-L non-M non-H histiocytoses
H group: haemophagocytic lymphohistiocytosis and macrophage activation syndrome
- primary haemophagocytic lymphohistiocytosis (Mendelian inherited conditions)
- secondary haemophagocytic lymphohistiocytosis (apparently non-Mendelian)
- haemophagocytic lymphohistiocytosis of unknown/uncertain origin