Impact of BRAFV600E mutation on aggressiveness and outcomes in adult clonal histiocytosis.

Histiocytoses encompass a wide spectrum of diseases, all characterized by tissue infiltration by CD68+ histiocytes. Most adult histiocytoses are considered clonal diseases because they highlight recurrent somatic mutations in the MAP-kinase pathway gene, primarily BRAF. The presence of BRAF mutation is associated with widespread disease in children with Langerhans cell histiocytosis (LCH) or cardiovascular/neurological involvement in Erdheim-Chester disease (ECD). Nevertheless, few data are available on adult clonal histiocytosis. This is why we have conducted a retrospective study of all patients with clonal histiocytosis in our institution and present the data according to the presence of BRAF mutation. Among 27 adult patients (10 ECD, 10 LCH, 5 Rosai-Dorfman disease (RDD), and 3 mixed ECD/LCH), 11 (39%) have BRAF mutation with gain of function (n = 9) and deletion (n = 2). Those patients had frequent multicentric disease with risk organ involvement, especially the brain and cardiovascular system. They had frequent associated myeloid neoplasms (mostly chronic myelomonocytic leukemia) and received more frequently targeted therapy as the front-line therapy. Nevertheless, its presence did not affect the overall survival or relapse-free survival probably due to the emergence of efficient therapies. To conclude, rapid and accurate molecular establishment in adult clonal histiocytoses is crucial because BRAFV600E mutation correlates with multicentric disease with organ involvement and incomplete metabolic response.

Efficacy of Rituximab on Rheumatoid Leptomeningitis as the First Symptom of Rheumatoid Arthritis.

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized mainly by arthritis, with the possible occurrence of extra-articular manifestations. We report the case of a patient who developed leptomeningitis as the first sign of RA, one year before the diagnosis of RA. Methylprednisolone 1000 mg was given intravenously. Because of the onset of seizures and cognitive impairment, rituximab was started. After three cycles of rituximab (1000 mg on day 0 and 1000 mg on day 15, every 6 months), neurological clinical examination, MRI and electroencephalogram findings were significantly improved. LEARNING POINTS: Rheumatoid meningitis may occur in the disease course of rheumatoid arthritis with varied and non-specific symptoms.Cerebrospinal fluid examination, MRI and tests for rheumatoid factor or anti-citrullinated protein antibodies in serum or in cerebrospinal fluid are key examinations for diagnosing rheumatoid meningitis.Rituximab has good efficacy in rheumatoid meningitis.