Erdheim-Chester Disease Successfully Treated with Front-Line Single-Agent Dabrafenib.

BACKGROUND Erdheim-Chester disease (ECD) is a clonal disease characterized by histiocytic infiltration of multiple organ systems. As ECD is a rare disorder with variable presentations, its diagnosis and management can present a significant clinical challenge. The diagnosis of ECD requires several clinical, radiological, and histological criteria. Since approximately 75% of ECD patients harbor a mutation in the proto-oncogene BRAF V600E, inhibition of BRAF activation by BRAF inhibitors has significantly improved the management of ECD. Vemurafenib was approved by the U.S. Food and Drug administration for treatment of BRAF-mutated ECD. Another BRAF inhibitor, dabrafenib, has been used in some cases as a single agent and was associated with a lower toxicity profile. CASE REPORT We report the case of a 30-year-old Saudi Arabian woman who initially presented with a history of diffuse abdominal pain and fever. The patient had elevated inflammatory markers, and radiological investigations revealed hypermetabolic regions in the frontoparietal brain lobe, anterior pericardium, kidneys, and the anterior abdominal wall. Histological investigations from the right perinephric soft-tissue mass revealed foamy histiocytes associated with mild chronic inflammation. Furthermore, BRAF V600E was mutated in the biopsy sample, leading to a diagnosis of BRAF-mutated ECD. The patient began single-agent dabrafenib therapy at 75 mg twice daily and experienced an excellent clinical and radiological response with no reported toxicity. CONCLUSIONS Single-agent dabrafenib is effective and well tolerated among ECD patients; therefore, it might be considered as a first-line option for the treatment of BRAF-mutated ECD.