A Case of Clinically Amyopathic Dermatomyositis that was Refractory to Intensive Immunosuppressive Therapy including Tofacitinib, but Successfully Treated with Plasma Exchange Therapy

ABSTRACT Clinically amyopathic dermatomyositis (CADM) patients often develop rapidly progressive interstitial lung disease (RP-ILD). A high level of anti-melanoma differentiation-associated gene 5 antibodies (anti-MDA5 Ab) before treatment is associated with RP-ILD development, a poor treatment response, and poor survival. The prognosis of CADM patients remains poor due to ILD even with combined intensive immunosuppressive therapy. Recently, several additional therapies, including tofacitinib (TOF) and plasma exchange (PE) therapy, have been reported to be effective. We herein report a case of CADM-ILD with a high level of anti-MDA5 Ab that was refractory to combined intensive immunosuppressive therapy including TOF, but successfully treated with PE. The following are possible reasons why TOF was ineffective: 1) cytokines that were not suppressed by TOF played an important role in RP-ILD; 2) TOF was administered later than previously reported; and 3) TOF did not suppress pathological substances such as antibodies. On the other hand, PE removes cytokines and various pathological substances. Therefore, PE may be a more reasonable additional therapy for intractable CADM-ILD.

Clinical Characteristics and Management of Patients With Clinical Amyopathic Dermatomyositis: A Retrospective Study of 64 Patients at a Tertiary Dermatology Department

Background: Clinical amyopathic dermatomyositis (CADM) represents a subtype of 5–20% of patients with dermatomyositis (DM), which can be categorized into amyopathic dermatomyositis (ADM) and hypomyopathic dermatomyositis (HDM). The characteristics of patients with CADM are still limited in English literature.Objective: To investigate clinical features, cutaneous findings, diagnostic accuracy, and treatment regimen of CADM patients.Methods: Sixty-four patients diagnosed with CADM at Peking Union Medical College Hospital by dermatologists were retrospectively analyzed. Data were recorded in the electronic database at each offline clinical consultation and directly extracted from medical records. 2017 EULAR/ACR criteria for idiopathic inflammatory myositis (IIM) classification was used to identify and classify patients with CADM. Published studies were searched to extract relevant data of CADM patients.Results: This cohort included 38 ADM patients and 26 HDM patients. 2017 EULAR/ACR criteria classified 67.2% of patients with CADM into probable or definite DM. Antimalarials were given to a majority of CADM patients (72.6%, n = 45). However, 68.8% (31 out of 45) required at least one aggressive agent combined with hydroxychloroquine due to insufficient response or side effects. The median of systemic treatments in HDM was significantly higher than ADM (p = 0.007). The number of ADM patients using antimalarials as monotherapy was significantly higher than that of HDM patients (p = 0.031), while the number of HDM patients receiving steroids combined with immunosuppressants was significantly higher (p = 0.025). The median of Cutaneous Dermatomyositis Disease Area and Severity Index (CDASI) score improvement was 11.5 and 10.5 for ADM and HDM after a median follow-up of 31.5 and 32.5 months, respectively. Six patients with normal muscle strength developed muscle weakness after a median of 10.5 months (IQR 9-13), and elevated inflammatory markers at initial visit might indicate their muscle weakness development.Conclusions: 32.8% of patients may be overlooked using the three skin variables of 2017 EULAR/ACR criteria. The response rate to single hydroxychloroquine in our cohort was 68.8%. Detailed treatment modalities were different among ADM and HDM. Long-term monitoring for the development of myositis in patients with CADM, especially those with elevated inflammatory markers at initial visit, may be warranted.

Performance of ENMC and EULAR/ACR classification systems applied to a single tertiary center cohort of dermatomyositis patients

Background There have been numerous classification systems to diagnose corresponding myositis subtypes and select appropriate therapeutic measures. However, the lack of a broad consensus on diagnostic criteria has led to clinical uncertainties. The objective of this study was to compare two commonly used dermatomyositis-classification systems regarding their clinical practicability and to point out their specific advantages and disadvantages. Methods This study included 30 patients diagnosed with dermatomyositis at the Charité university hospital, Berlin, Germany from 2010 to 2017. Patient files with complete data and defined historical classifications were enrolled and ENMC (2003) and EULAR/ACR (2017) criteria retrospectively applied. Results According to the ENMC approach, 14 patients were classified as "definite" and 12 as "probable" dermatomyositis. One patient exhibited an "amyopathic dermatomyositis" and three a "DM without dermatitis". Regarding the criteria probability of the EULAR/ACR set, 16 patients had a "high", 13 a "medium" and one a "low probability". There was a significant difference (p = 0.004) between the subclasses of the ENMC in relation to the EULAR/ACR score. The agreement between the classification probabilities of "definite/high" (κ = 0.400) and "possible/medium" (κ = 0.324) was fair. Conclusions It is important to find a consensus among the medical disciplines involved and to establish a structured procedure. Future studies with newer approaches are warranted to conclusively decide which system to use for the physician.