[Erdheim-Chester disease associated with Langerhans cell histiocytosis: A case of a mixed form]

Langerhans cell histiocytosis and Erdheim-Chester disease are rare inflammatory myeloid neoplasms. They present characteristic clinical, histological and radiological signs. Their association is exceptional. We report a new observation.

A 47-year-old man presented with lesions of seborrheic dermatitis-like, intracranial hypertension, paralysis of the sixth cranial nerve, and central diabetes insipidus. The skin biopsy concluded that there was Langerhans cell histiocytosis. The bone scan showed metaphyseal-diaphyseal osteosclerotic lesions of the femur, tibia and humerus. The thoraco-abdomino-pelvic CT scan showed an aortic sheathing, suggesting Erdheim-Chester disease. The search for the BRAF^V600E mutation was negative. The patient was treated with oral corticosteroid therapy then with cladribine which allowed a good evolution.

We report an observation of a mixed form of histiocytosis associating Langerhans cell histiocytosis and Erdheim-Chester disease, with a diagnostic delay of ten years, and having responded well to treatment with cladribine.