[Nosologic overview of the spectrum of cutaneous histiocytoses. The more things change, the more they stay the same].

Histiocytes belong to distinct groups of cells. Similarly, histiocytoses represent some pathologic expressions of the various histiocyte lineages recognized by their distinct phenotypes. The recognition of four major histiocytosis types relies on the distinction between monocytes-macrophages, dermal dendrocytes, Langerhans cells and the so-called indeterminate cells. Each of these groups exhibits a distinctive clinical and histological presentation. The risk of internal involvement, the prognosis and therapy are different as well. The diagnostic mainly relies on the clinico-pathologic assessment, and more particularly on the combination of histological, immunohistochemical and ultrastructural examinations.