Lung Involvement in Destombes-Rosai-Dorfman Disease: Clinical and Radiological Features and Response to the MEK Inhibitor Cobimetinib.

BACKGROUND: Destombes-Rosai-Dorfman disease (RDD) is a rare multisystemic histiocytosis. Pulmonary involvement during RDD has been poorly described. The goal of this study was to examine the clinical presentations, radiological features, and outcomes of 15 patients with RDD and lung involvement.

METHODS: The cases of RDD with lung involvement were extracted from the French National Histiocytosis registry. Efficacy of the MEK inhibitor cobimetinib in treating lung disease was evaluated with an 18 fluorodeoxyglucose PET scanner and chest CT scans.

RESULTS: Fifteen patients (six women; median age, 40 years at RDD diagnosis) were included. All patients had evidence of systemic disease with extrapulmonary localizations of the disease (lymphadenopathy [n = 12], skin [n = 9], bones [n = 6], retroperitoneal involvement [n = 3], sinuses [n = 3], parotid gland [n = 2], submandibular gland [n = 1], and breast [n = 1]). Presenting symptoms were dominated by dyspnea and dry cough in seven patients. Restrictive physiology was observed in two of five patients. BAL showed lymphocytosis in one of five cases. Eight patients received corticosteroids, all but one with variable immunosuppressive or immunomodulatory therapies. Two patients received cobimetinib for severe lung disease, with dramatic pulmonary metabolic and tumoral responses. Two patients died during follow-up: one of hemoptysis, and the other of an unrelated cerebral tumor.

CONCLUSIONS: Pulmonary involvement in RDD is rare, proteiform, and sometimes severe. The MEK inhibitor cobimetinib can lead to dramatic responses.