Primary histiocytic dermatoses

The physiology of the histiocyte (macrophage) in health and disease is reviewed briefly. An overview of the so-called primary malignant, pseudomalignant, and benign histiocytic disorders, excluding histiocytosis X, is presented. The malignant histiocytosis with erythrophagocytosis, the pseudomalignant histiocytic diseases (such as sinus histiocytosis with massive lymphadenopathy and regressing atypical histiocytosis), and the solitary lesions with histologic malignant and atypical storiform histiocytosis are described. Two groups of adult histiocytic diseases are reviewed; one is characterized by nonfamilial and familial histiocytic dermatoarthritis and the other by multiple widespread benign lesions, such as xanthoma disseminatum, generalized eruptive histiocytoma, nodular non-X histiocytosis, and various xanthomatous eruptions associated with paraproteinemia. Finally, multiple benign cutaneous histiocytic lesions of childhood, such as juvenile xanthogranuloma and congenital self-healing histiocytosis, are included.