Relapsing pleural effusions and coated aorta revealing Erdheim-Chester disease

Tiépé Rokia Ouattara¹Théo Pezel²Gwenael Lorillon³Aïcha Kante⁴Peggy Reiner⁵Aurélie Le Gal³Marine Lefèvre⁶Thibault Vieira⁶Stéphane Mouly⁵Abdellatif Tazi³Julien Haroche⁷Trecy Goncalves¹Damien Sène^4,8Jean-François Emile⁹Cloé Comarmond^1,10*Cloé Comarmond^1*

• ¹Hôpital Lariboisière, Paris, France
• ²Département de cardiologie, Hôpital Lariboisière, Paris, France
• ³Saint-Louis Hospital, Paris, France
• ⁴Médecine Interne et Immunologie Clinique, Hôpital Lariboisière, Paris, France
• ⁵Lariboisière Hospital, Paris, France
• ⁶L'Institut Mutualiste Montsouris, Paris, France
• ⁷Hôpitaux Universitaires Pitié Salpêtrière, Paris, France
• ⁸lariboisière hospital, Paris, France
• ⁹Hôpital Pitié-Salpêtrière, Paris, France
• ¹⁰Université de Paris, Paris, France

Erdheim-Chester disease (ECD) is a rare histiocytic disorder with localized presentations or multisystem disease. Clinical manifestations of ECD are usually non-specific and depends on the site of involvement. ECD can involve single or multiple organs, and presentations range from asymptomatic lesions detected incidentally on imaging to severe and life-threatening organ dysfunction. Hence, accurate and timely diagnosis is challenging given the rarity and varied presentation of ECD. The most common clinical manifestations are bone pain related to osteosclerosis, usually in the lower limbs. We report here a case with no obvious clinical manifestation of ECD preceding initial recurrent pleural effusions. The diagnosis of ECD was suggested based on pleural thickening revealed by relapsing pleural effusions combined with radiological finding of a coated aorta and slight perirenal infiltrate. Pleural biopsy revealed collagen fibrosis and immunohistochemistry with anti-CD163 antibody showed an important infiltration by histiocytes, strong cytoplasmic phosphorylated ERK in the lesional cells and positive factor XIIIa staining. A cell-free DNA from peripheral blood revealed negative BRAF mutation but the presence of MAP2K1 mutation, key driver mutation in ECD. While the final diagnosis is established by histopathology, the initial diagnosis is often suggested based on clinic-radiological presentation, and plasma cell-free DNA is a promising and non-invasive tool to detect key driver mutations.