Dabrafenib and steroids for the treatment of Erdheim-Chester disease with extensive CNS involvement: a case report.

Erdheim-Chester disease (ECD) is an exceedingly rare non–Langerhans cell CD68⁺ CD1a^- S100^- histiocytic multi-organ disease. Diagnosis of ECD is often delayed due to non-specific radiographic findings and heterogeneous lesional tissue. Increasingly, the role of genomic alterations is being recognized for both diagnosis and treatment of ECD. More than half of ECD patients harbor the BRAF^V600E mutation. Evaluation for this mutation be can falsely negative on immunohistochemical staining and confirmation with molecular analyses is recommended. We present a case of the 44 year-old male with BRAF^V600E-positive ECD treated successfully with steroids followed by single-agent dabrafenib. Plain language summary Erdheim-Chester disease (ECD) is an exceedingly rare type of histiocytosis (a disorder of white blood cells). The diagnosis of ECD can be challenging because tissue biopsy may not provide a definitive diagnosis. Currently, genetic mutations can be used to support both diagnosis and treatment. We present a case of the 44 year-old male with BRAF V600E -positive ECD who was treated successfully with steroids followed by dabrafenib. Executive summary Erdheim-Chester Disease (ECD) is exceedingly rare. ECD with central nervous system involvement can be refractory to conventional therapies. Steroids may be therapeutic for ECD. Molecular profiling should be obtained to assess for BRAF^V600E mutation, regardless of a negative immunohistochemical BRAF immunohistochemical staining. BRAF inhibitors should be considered as first-line therapy for BRAF^V600E-positive ECD patients. [ABSTRACT FROM AUTHOR]