| • | begins as a promonocyte in the bone marrow and is released into the blood stream as a monocyte |
Langerhan’s cell histiocytosis (CD1a and S-100 positive):
non-Langerhans’s cell histiocytosis (CD1a and S-100 negative):
Normolipidemic xanthomatoses lesions composed of foamy cells (i.e. xanthoma cells) and Touton giant cells:
| • | JXG (self-healing 3 to 6 years) |
| • | xanthoma disseminatum (persistent form most common) |
| • | papular xanthoma (self-healing 1 to 5 years) |
| • | necrobiotic xanthogranuloma (chronic often progressive) |
No "foamy" cells:
| • | generalized eruptive histiocytosis |
| • | benign cephalic histiocytosis |
| • | multicentric reticulohistiocytosis |
definitions:
|
Histiocytic infiltrates of the skin – Langerhans cell and non-Langerhans cell proliferations in which lipid accumulation (xanthomatization) may be a secondary phenomenon
Xanthomas – the accumulation of lipid-rich macrophages known as foam cells; usually associated with disorders of lipoprotein metabolism
Xanthogranuloma – essentially xanthomas that are not related to disorders of lipoprotein metabolism (foam cells and Touton giant cells e.g. NXG, JXG)