Acral histiocytic nodules: a possible new variant of non-X histiocytosis

Many types of histiocytoses have been described. We present a case of a 56-year-old woman who presented with multiple nodules on the hands. On histological examination of an excision biopsy, a mainly dermal lesion was seen, with scattered mononuclear inflammatory cells and occasional multinucleated cells in the background. The tumour was composed of short spindle-shaped histiocyte-like cells with vesicular nuclei and small nucleoli. These cells were positive for CD68 and focally positive for smooth-muscle actin. There was no lipid or haemosiderin pigment, and no cholesterol clefts. Further investigations did not find evidence of bony or systemic involvement. The non-Langerhans cell histiocytoses, also known as non-X histiocytoses, are rare and of unknown aetiology. Clinicopathologically, this case does not seem to fit with any of the recognized subtypes, and we propose that it may represent a previously undescribed variant of the disease.