Progressive nodular histiocytosis.

Progressive nodular histiocytosis (PNH) represents a very rare type of non-Langerhans cell histiocytosis (NLCH). It can be distinguished from other types by the occurrence of yellow to red-brown papules and nodules measuring a few centimeters in size. Histologically the nodules represent spindle-cell xanthogranulomas. We report on two new cases of PNH with novel clinical symptoms. In the first case, the patient had microcytic anemia due to massive iron deposition in the nodules and a progressively worsening limp due to involvement of the soles. The complex therapeutic challenge was effectively managed by successive surgical ablation of all visible lesions. The second patient had epibulbar infiltrates. The clinical variability of PNH leads to considerable overlap with other forms of NLCH.