Accesory cells
Histiocytic and dendritic cells
• Ag presenting cells: dendritic
• Ag processing: histiocytes
• Histiocytes: phagocytic
Removal of particulate Ag
Derived from blood monocytes
Dendritic cells
In various tissues, lymph node:
• Interdigitating
• Follicular
• Fibroblastic reticular
Diseases of DC and histiocytes
• Tumours of histiocytes and dendritic cells
• Langerhans cell histiocytosis (/sarcoma)
• Dendritic cell tumour – follicular, interdigitating,
NOS
Hemophagocytic syndrome
• Nonneoplastic but frequently fatal
proliferation of histiocytes
• More common than tumours of histioc.
• Complication of immunodeficiency or
haematolymphoid malignancy
• Often EBV-triggered
Hemophagocytic syndrome
• Excessive production of cytokines
- cytokine storm
Pancytopenia
Aggressive, disseminates rapidly
Responds poorly to therapy. Often fatal
Localization: LN or extranodal sites
Morphology: large cells: histiocytes with
atypia
Histiocytic
and dendritic cell neoplasms
• Rarest of the hematolymphoid neoplasms
• Any age
• Presentation and processing of Ag to
lymphocytes
Langerhans cell histiocytosis
Synonyms:
Langerhans cell granulomatosis
Histiocytosis X
Langerhans cell histiocytosis
• Children
• Adults
• Incidence: 0,5-1 case /100 000 a year
• Localization: bone (pain, fractures,
vertebral collapse), soft tissues
• Skin; lungs – adult smokers
• LN, liver, BM
Langerhans cell histiocytosis
• Mortality - variable
• Highest in children under 2 (30-50%)
• Liver, lungs, BM, spleen, penetrating skull
lesions
Langerhans cell histiocytosis
1.unisystem, unifocal - good prognosis
Adults, older chidren
Bone (lytic)- skull, femur, ribs, pelvis
Arrely other - lymph node, skin, lung
2. Unisystem, multifocal (Hand-Schuller-Christian
Young children, multiple destructive - bones
Exophthalmos, dib. insipidus, tooth loss
3. Multifocal, multisystem (Apt-Letterer-Siwe)
Infants, fever, ↑H+S, lymph nodes, pancytopenia
Langerhans cell histiocytosis
4. Pulmonary Langerhans cell histiocytosis
• Fibrosing interstitial disease, honeycombing,
pneumothorax
• Variable outcome
• mortality 25%
• Cessation of smoking
• Corticosteroids
5. Langerhans cell sarcoma
Disseminated Langerhans histiocytosis
haemorrhagic eczematoid rash
(10 months)
Disseminated Langerhans histiocytosis
osteolytic deposits in the vault
Langerhans cell sarcoma
Skin - hair
Neoplastic
Langerhans cells
Imunohistochemistry
CD1a +
„ Coffee bean“
nuclei of LC cells
and eosinophils