BACKGROUND Cutaneous histiocytosis of childhood often regresses spontaneously without treatment. In some cases however, it is difficult to differentiate aggressive forms and electron microscopy and immunohistochemistry can be a valuable help. We report a case of cutaneous histiocytosis in a child which illustrates the difficulties encountered in the classification of histiocytosis. METHODS An 18-month old girl was brought to consultation with a cutaneous nodule which had developed at the age of 15 months on the labia majora. A second nodule on the chin had regressed spontaneously. Histology showed evidence of dermal histiocyte proliferation. Immunohistochemistry demonstrated is non Langerhans nature which was confirmed by electron microscopy. The clinical course was benign after surgical exeresis of the lesion on the labia majora. CONCLUSIONS Different forms of histiocytosis can be classed on the basis of 4 criteria: Langerhans origin or not, acquired or congenital forms, cutaneous or visceral involvement, benign or malignant course. Four diagnosis were possible in our case: histiocytosis X, self-healing congenital histiocytosis, benign cephalic histiocytosis, juvenile xanthogranuloma. We preferred to use the descriptive term of acquired regressive cutaneous non-X histiocytosis of childhood.