A case of non-Langerhans histiocytosis effectively treated with Cobimetinib: A rare case report

non-Langerhans histiocytosis is a group of very rare, clinically heterogeneous diseases, characterized by the proliferation of histiocytes in the connective tissue, it preferentially affects middle-aged men, their classification is difficult, it is based on clinical, histological, immune criteria histochemical and evolutionary.
We report the case of a 58-year-old man with an HIV infection under treatment. The patient initially presented with skin lesions, the skin biopsy was in favor of xanthoma disseminatum, and then the patient presented with bone pain and respiratory symptoms. , the extension assessment and the biopsies confirm the diagnosis of Erdheim-Chester disease with bone, cardiac, aortic and pulmonary involvement and diffuse skin involvement « disseminated xanthoma », the patient was put on Cobimetinib 20 mg / day which resulted in an excellent clinical and radiological response with no reported toxicity.
Cobimetinib is effective and well tolerated in cases of Erdheim-Chester disease; therefore, it could be considered as a good therapeutic option as a monotherapy for patients without BRAF mutation.