Langerhans cell histiocytosis first presenting in the skin in adults:frequent association with a second haematological malignancy

Background Langerhans cell histiocytosis (LCH) in adults first presenting in the skin is rare. Guidelines for staging, treatment and follow-up are lacking.Objectives To better define staging procedures, treatment results and clinical course in adult patients with LCH first presenting in the skin.Methods Eighteen adult patients with LCH first presenting in the skin were collected from five centres collaborating in the Dutch Cutaneous Lymphoma Group. Clinical records and (skin) biopsy specimens were reviewed and follow-up data were obtained. A literature search on adult patients with LCH presenting in the skin was performed.Results Staging procedures showed extracutaneous disease in three of 16 patients who were adequately staged. One patient had a histologically confirmed lytic LCH bone lesion, while two patients had a myelodysplastic syndrome. During follow-up two of 18 patients developed extracutaneous localizations of LCH. Five patients developed a second haematological malignancy, including (myelo)monocytic leukaemia (two cases), histiocytic sarcoma (one case), diffuse large B-cell lymphoma (one case) and peripheral T-cell lymphoma (one case). Review of the literature revealed six other adult patients with a second haematological malignancy preceding or following a diagnosis of LCH.Conclusions The results of the present study suggest an increased risk of a second haematological malignancy in adult patients with LCH presenting in the skin. Extensive staging at presentation and long-term follow-up are therefore warranted in such patients.