Anti-Mi2 Dermatomyositis Revisited: Pure DM Phenotype with Muscle Fiber Necrosis and High Risk of Malignancy

Océane Landon-Cardinal¹, Grégoire Monseau², Yoland Schoindre³, Aude Rigolet¹, Nicolas Champtiaux¹, Baptiste Hervier¹, Agathe Masseau⁴, Eric Hachulla⁵, Thomas Papo⁶, Benjamin Terrier⁷, Alain Meyer⁸, Jean-Emmanuel Kahn³, François Maurier⁹, Francis Gaches¹⁰, Emmanuelle Salort-Campana¹¹, Thierry Zenone¹², Nathalie Costedoat-Chalumeau⁷, Florian Perez¹³, Maxime Samson¹⁴, Anne-Marie Piette³, Guillaume Moulis¹⁰, Sylvain Audia¹⁵, Séverine Genot¹⁶, Nicolas Schleinitz¹⁷, Guillaume Lefevre⁵, Laurence Verneuil¹⁸, Olivier Benveniste¹⁹, Yves Allenbach¹ and Boris Bienvenu²⁰, ¹Internal Medicine, Pitié-Salpêtrière University Hospital, Paris, France, ²Internal Medicine, Caen University Hospital, Caen, France, ³Internal Medicine, Foch Hospital, Suresnes, France, ⁴Internal Medicine, Nantes University Hospital, Nantes, France, ⁵Internal Medicine, Lille University Hospital, Lille, France, ⁶Bichat University Hospital - Internal Medicine, Paris, France, ⁷Internal Medicine, Cochin University Hospital, Paris, France, ⁸Rheumatology, Strasbourg University Hospital, Strasbourg, France, ⁹Internal Medicine, Sainte-Blandine de Metz Hospital, Metz, France, ¹⁰Internal Medicine, Toulouse University Hospital, Toulouse, France, ¹¹Neurology, La Timone University Hospital, Marseille, France, ¹²Internal Medicine, Valence Hospital, Valence, France, ¹³Neurology, Albi Hospital, Albi, France, ¹⁴Dijon University Hospital, Dijon, France, ¹⁵Internal Medicine, Dijon University Hospital, Dijon, France, ¹⁶Internal Medicine, Martigues Hospital, Martigues, France, ¹⁷La Timone University Hospital, Marseille, France, ¹⁸Dermatology, Caen University Hospital, Caen, France, ¹⁹Pitié-Salpêtrière University Hospital, Paris, France, ²⁰Caen University Hospital, Caen, France

Meeting: 2016 ACR/ARHP Annual Meeting

Date of first publication: September 28, 2016

Keywords: Cancer, dermatomyositis and myositis

Session Information

Date: Tuesday, November 15, 2016

Session Title: Muscle Biology, Myositis and Myopathies - Poster II: Clinical

Session Type: ACR Poster Session C

Session Time: 9:00AM-11:00AM

Background/Purpose: Anti-Mi2 autoantibodies (Aabs) have been proposed to be highly specific for dermatomyositis (DM) and to be associated with a DM classical phenotype consisting of typical skin rashes and low extra-muscular features. Cancer has been estimated in about 30% of all DM patients. Patients with anti-Mi2 DM are considered having a good prognosis, possibly related to a markedly lower risk of malignancy reported in this subset. Nonetheless, there has been only a few and small cohort descriptions of this DM subgroup. Our objective was therefore to describe the phenotype of anti-Mi-2 DM in a large French cohort.

Methods: A national multicenter retrospective cohort study was performed (15 medical centers) including all patients with a clinical phenotype suggestive of DM (cutaneous manifestations and/or muscle involvement) and a positive anti-Mi2 Aabs. Medical records were retrospectively reviewed. Muscle strength was assessed using the Medical Research Council (MRC) scale and cancer-associated myositis (CAM) was defined as a cancer occurring ± 3 years of diagnosing myositis.

Results: A total of 65 patients were identified, 62% were female and mean age at diagnosis was 54 years old (yo) (±17 yo). DM skin rash was reported in 88% of patients, most frequently Gottron papules and/or sign (68%), periungueal erythema (51%) and heliotrope rash (40%). Peripheral muscle weakness was reported in 92% of patients and dysphagia was reported in 34% of patients. At diagnosis, patients displayed severe muscle weakness (MRC 3/5, ±1/5) with mean CK level of 5085 UI/L (±5535 UI/L). Systematic review of muscle biopsies (n=11) showed marked inflammatory infiltrates. Strikingly, necrosis and regeneration were identified in all patients (n=11/11). C5b-9 deposition was found in all patients mainly on non-necrotic fibers but only sparsely on capillaries and without prominent capillary loss. Arthritis, Raynaud phenomenon and interstitial lung disease were reported in less than 20 % of patients. CAM was identified in 20% of patients and detected within one year and a half of DM diagnosis in most patients (n=11/12). All CAM patients, but one (38 yo), were diagnosed over 50 yo. There was no predominant histological subtype of malignancy (gastro-intestinal, urological, gynecological and pulmonary) and cancer was metastatic in a third of patients. Survival rate was 83% after a mean follow-up of 4.9 years from cancer diagnosis. Ninety-eight percent of patients were initially treated with corticosteroids (CS), in combination with immunosuppressant (IS) in 60% of cases. Patients treated with CS monotherapy (n=14), needed second-line agents upon follow-up in 60% of cases. In all, 53% of patients relapsed upon CS and/or IS tapering.

Conclusion: In this large French cohort, patients with anti-Mi2 DM displayed a phenotype with 3 main characteristics (i) pure DM phenotype (low overlap features) (ii) necrotizing myositis (severe weakness, high CK level and muscle fiber necrosis) and (iii) higher than expected malignancy rate.

Disclosure: O. Landon-Cardinal, None; G. Monseau, None; Y. Schoindre, None; A. Rigolet, None; N. Champtiaux, None; B. Hervier, None; A. Masseau, None; E. Hachulla, None; T. Papo, None; B. Terrier, None; A. Meyer, None; J. E. Kahn, None; F. Maurier, None; F. Gaches, None; E. Salort-Campana, None; T. Zenone, None; N. Costedoat-Chalumeau, None; F. Perez, None; M. Samson, None; A. M. Piette, None; G. Moulis, None; S. Audia, None; S. Genot, None; N. Schleinitz, None; G. Lefevre, None; L. Verneuil, None; O. Benveniste, None; Y. Allenbach, None; B. Bienvenu, None.

To cite this abstract in AMA style:

Landon-Cardinal O, Monseau G, Schoindre Y, Rigolet A, Champtiaux N, Hervier B, Masseau A, Hachulla E, Papo T, Terrier B, Meyer A, Kahn JE, Maurier F, Gaches F, Salort-Campana E, Zenone T, Costedoat-Chalumeau N, Perez F, Samson M, Piette AM, Moulis G, Audia S, Genot S, Schleinitz N, Lefevre G, Verneuil L, Benveniste O, Allenbach Y, Bienvenu B. Anti-Mi2 Dermatomyositis Revisited: Pure DM Phenotype with Muscle Fiber Necrosis and High Risk of Malignancy [abstract]. Arthritis Rheumatol. 2016; 68 (suppl 10). https://acrabstracts.org/abstract/anti-mi2-dermatomyositis-revisited-pure-dm-phenotype-with-muscle-fiber-necrosis-and-high-risk-of-malignancy/. Accessed January 24, 2021.

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