Review

MDA5 dermatomyositis: Unveiling a potentially life-threatening disease

Soumya Chatterjee, MD, MS
Cleveland Clinic Journal of Medicine October 2025, 92 (10) 627-637; DOI: https://doi.org/10.3949/ccjm.92a.25018

ABSTRACT

Melanoma differentiation–associated gene 5 (MDA5) dermatomyositis, characterized by antibodies targeting MDA5, has recently emerged as a distinct subset of the idiopathic inflammatory myopathies. It is identified by distinctive clinical manifestations, including fever, characteristic skin lesions, nonerosive symmetrical polyarthritis, and rapidly progressive interstitial lung disease (ILD); often there is minimal to no muscle involvement. Classifying the disease into rapidly progressive ILD, rheumatic, and vasculopathic subtypes, as reported in some studies, may help predict prognosis. Prompt recognition of its unique clinical manifestations and initiation of aggressive immunosuppressive therapy are vital to improve outcomes in this potentially life-threatening condition.

KEY POINTS

  • MDA5 dermatomyositis is an interferon-mediated vasculopathy defined by anti-MDA5 antibodies, with characteristic skin and lung involvement.

  • It differs from classical dermatomyositis in pathophysiology and clinical course.

  • Rapidly progressive ILD with diffuse alveolar damage drives severity and mortality.

  • Anti-MDA5 antibody titers and serum ferritin levels predict prognosis and response.

  • Rapidly progressive ILD requires intensive combination immunosuppression, though efficacy is limited and toxicity is considerable.

Idiopathic inflammatory myopathies are a heterogeneous group of autoimmune rheumatic disorders that cause chronic inflammation of skeletal muscles (myositis), but can also affect the skin, joints, lungs, heart, and gastrointestinal tract, indicating that these disorders are systemic.1

Dermatomyositis, a subset of idiopathic inflammatory myopathies, is marked by distinctive skin manifestations.2 Its hallmark cutaneous manifestations include a heliotrope rash, Gottron papules, and Gottron sign,2 discussed in more detail below, while myositis commonly manifests as proximal muscle weakness. Dysphagia may result when the striated muscles of the oropharynx and upper esophagus are involved. In clinically amyopathic dermatomyositis, however, muscle weakness is absent.2

Various myositis-specific antibodies have been associated with the idiopathic inflammatory myopathies.3 These autoantibodies target specific intracellular proteins, which can guide the clinician in diagnosing the subtype of idiopathic inflammatory myopathy, predicting the disease course, and tailoring treatment strategies.3 The anti–melanoma differentiation– associated gene 5 (MDA5) dermatomyositis antibody is a myositis-specific autoantibody linked to clinically amyopathic dermatomyositis and rapidly progressive interstitial lung disease (ILD).4

Given the increasing prevalence of MDA5 dermatomyositis in recent years,4 clinicians should be able to promptly recognize its unique phenotype, as timely intervention with aggressive immunosuppressive therapy is key to improving the prognosis of patients with MDA5 dermatomyositis–associated rapidly progressive ILD. The anti-MDA5 antibody is an essential biomarker that helps clinicians identify MDA5 dermatomyositis in the appropriate clinical context. However, the complexity of the disease’s pathophysiology, prognostic indicators, and therapeutic strategies present ongoing challenges and are areas for further exploration. The case below highlights some of these challenges.

ILLUSTRATIVE CASE

A 58-year-old woman presents with an itchy rash that resembles folliculitis. Physical examination reveals bibasilar rales and a maculopapular, blistering rash over her neck, chest, abdomen, and thighs.

Routine laboratory test results are within normal limits. Her creatine kinase is 350 U/L (reference range 30–220), and serum ferritin is 1,237 ng/mL (18–300). Tests for antinuclear antibodies, antibodies to extractable nuclear antigens, and antineutrophil cytoplasmic antibodies are negative. The results from the available myositis-specific antibody panel, including antisynthetase, anti–Mi-2, and anti–signal recognition particle antibodies, are also negative.

Chest radiograph reveals hypoinflated lungs with bilateral lower-lobe opacities consistent with early pulmonary edema. Echocardiography shows a low-normal ejection fraction of 53%. She is started on furosemide for suspected heart failure.

Within a few weeks of her initial presentation, the patient develops progressive exertional dyspnea. She subsequently experiences a 14-lb (6.35-kg) weight loss, her hypoxia worsens and she requires home oxygen, and she develops ulcerated Gottron papules and tender palmar papules. Pulmonary function tests reveal severe restriction:

  • Forced vital capacity 63% of predicted

  • Forced expiratory volume in 1 second 62% of predicted

  • Carbon monoxide diffusing capacity 33% of predicted.

Thoracic noncontrast high-resolution computed tomography (CT) reveals organizing pneumonia and interstitial pneumonitis.

Despite the previous negative results from the available myositis serologies, her clinical phenotype strongly suggests MDA5 dermatomyositis. An extended myositis antibody panel is sent to an external reference laboratory.

While awaiting serology to confirm the diagnosis, the patient is empirically treated with intravenous methylprednisolone 1,000 mg daily for 3 days, followed by prednisone 60 mg daily and tacrolimus 5 mg twice daily. Treatment with cyclophosphamide or mycophenolate mofetil is delayed due to medical insurance denials. The patient also receives antibiotics and diuretic therapy.

Two months after the extended myositis antibody panel was sent, results confirm anti-MDA5 antibodies.

Eight months after her initial presentation, the patient is hospitalized with worsening respiratory failure, hemoptysis, thrombocytopenia, and liver dysfunction. High-resolution CT shows worsening ILD with architectural distortion. Lung biopsy reveals organizing acute lung injury with neutrophilic infiltration in the septal capillaries and alveolar spaces, intra-alveolar fibrin, and reactive type II pneumocytes. An extensive infectious disease workup is negative. Despite intensive treatment efforts, she deteriorates rapidly and dies shortly after being admitted to the hospital.

Prompt diagnosis is key

This patient’s case highlights the aggressiveness of MDA5 dermatomyositis, particularly with refractory rapidly progressive ILD and multiorgan involvement. Systemic barriers, including delays in receiving results of the extended myositis antibody panel and insurance denial of immunosuppressive therapy, likely exacerbated her disease progression. Given the limited availability of serologic testing to confirm MDA5 dermatomyositis, significant delays in obtaining results from external reference laboratories, and the poor prognosis of rapidly progressive ILD, it is imperative to promptly diagnose and start aggressive immunosuppressive therapy based on a strong clinical suspicion of MDA5 dermatomyositis–associated rapidly progressive ILD— even before the diagnosis is confirmed—to treat this relatively rare but potentially fatal autoimmune disease.

EPIDEMIOLOGY

MDA5 dermatomyositis was first described in 2005 by Sato et al5 in a Japanese cohort with clinically amyopathic dermatomyositis and rapidly progressive ILD. Later studies showed that anti-MDA5 antibody prevalence varies across different dermatomyositis populations. For example, 37.3% of patients in a Japanese cohort with dermatomyositis tested positive for anti-MDA5 antibodies.6 Conversely, the prevalence in a North American cohort was 6.9%.7 A Canadian study found that the median age at diagnosis was 52 years, and 71% of the patients were Asian, predominantly of Chinese descent, and 29% were White.8 MDA5 dermatomyositis is also more prevalent in women.8

PATHOGENESIS

Proposed factors implicated in the pathogenesis of MDA5 dermatomyositis include genetic predisposition, environmental triggers (eg, viral infections), and immune dysregulation.9 MDA5 senses viral double-stranded RNA and in response activates type I interferon pathways, primarily interferon alpha, triggering inflammation. Anti-MDA5 antibodies amplify production of interferon alpha and immune activation, leading to the formation of immune complexes that exacerbate tissue injury. Key features of immune dysregulation caused by anti-MDA5 antibodies include excessive interferon activity, vascular damage, and fibrosis, especially in the skin and lungs. Endothelin-mediated vasoconstriction contributes to tissue ischemia, while alveolar macrophages drive lung fibrosis via synthesis of transforming growth factor beta and fibroblast activation.

These mechanisms suggest shared pathways with other interferonopathies, and are potential therapeutic targets.9 Additional discussion of the proposed complex pathogenesis of MDA5 dermatomyositis is beyond the scope of this review.

LABORATORY FEATURES

Anti-MDA5 antibodies are typically measured using enzyme-linked immunosorbent assay or other validated immunoassays.9 However, immunoprecipitation remains the gold standard.5 While anti-MDA5 antibody titers may correlate with disease activity and ILD severity, routine measurement has a limited impact on clinical decision-making.

Elevated serum ferritin levels correlate with disease severity and ILD.10 Liver dysfunction (defined as elevated alanine transaminase and aspartate transaminase and normal creatine kinase levels) is common, and biopsies will show hepatocyte ballooning and steatosis.11 Hepatic transaminases may rise when ferritin levels increase and ILD worsens.9

In addition, anti-Ro52 antibody co-occurrence predicts a poor prognosis.9

CLINICAL FEATURES

Constitutional symptoms

A study showed that approximately 74% of Japanese patients present with fever at disease onset,12 although rates in US patients are likely lower. Fatigue and weight loss are common at presentation or during relapses.13

Mucocutaneous manifestations

The typical skin manifestations seen in classic dermatomyositis are also seen in patients with MDA5 dermatomyositis2:

  • Periorbital swelling accompanied by a purple or violet heliotrope rash (Figure 1A)

  • An erythematous facial rash that extends across the nasolabial folds

  • Erythema over the anterior chest (known as the V-sign) (Figure 1B)

  • Erythema over the back and shoulders (known as the shawl sign).

Mucocutaneous manifestations of melanoma differentiation–associated gene 5 dermatomyositis. (A) Heliotrope rash. (B) Erythematous rash on the anterior chest (V sign). (C) Tender, violaceous palmar papules (inverse Gottron papules). (D) Skin ulcerations on both forearms. (E) Violaceous papules in a linear distribution on the radial margin of the right index finger. (F) Ulcerated Gottron papules. (G) Ulcerated Gottron lesion over the left elbow. (H) Gangrene of the distal end of the right fifth finger. (I) Ulcer on the helix of the left ear. (J) Oral ulcers (arrows). (K) Diffuse alopecia.
Figure 1

Mucocutaneous manifestations of melanoma differentiation–associated gene 5 dermatomyositis. (A) Heliotrope rash. (B) Erythematous rash on the anterior chest (V sign). (C) Tender, violaceous palmar papules (inverse Gottron papules). (D) Skin ulcerations on both forearms. (E) Violaceous papules in a linear distribution on the radial margin of the right index finger. (F) Ulcerated Gottron papules. (G) Ulcerated Gottron lesion over the left elbow. (H) Gangrene of the distal end of the right fifth finger. (I) Ulcer on the helix of the left ear. (J) Oral ulcers (arrows). (K) Diffuse alopecia.

Other hallmark features are Gottron papules, which are violaceous papules or plaques on the dorsal surfaces of the metacarpophalangeal and interphalangeal joints; cuticle overgrowth with nailfold capillary abnormalities; and thickened, fissured skin on the tips and margins of fingers, commonly referred to as mechanic’s hands.2 Although this skin manifestation is seen less frequently in MDA5 dermatomyositis than in antisynthetase syndrome,3 the presence of mechanic’s hands should raise concern because it is strongly associated with rapidly progressive ILD.14

More specific and distinct cutaneous manifestations seen in both White and Asian patients with MDA5 dermatomyositis include tender palmar papules referred to as inverse Gottron papules2 (Figure 1C) and skin ulcerations (Figure 1D).12,15 Palmar papules are typically found on the volar surfaces or edges of the fingers, particularly over the metacarpophalangeal and interphalangeal joints (Figure 1C and Figure 1E).15 These tender lesions, the center of which may be ivory colored, are exquisitely painful and may become hyperkeratotic and ulcerate (Figure 1C).9,15 Skin ulcerations are typically deep and painful and often involve Gottron papules (Figure 1F).15 They can also affect the digital pulp and nailfolds or occur over Gottron lesions on the knees and elbows (Figure 1G).15 Digital gangrene (Figure 1H) and osteomyelitis may occur, which can require amputation.9,13

Less specific skin manifestations include violaceous or erythematous papules and ulcers on the helix and antihelix of the ears (Figure 1I),6 which are considered a poor prognostic marker. Oral ulcers (Figure 1J), panniculitis, alopecia (Figure 1K), and flagellate erythema are also less characteristic manifestations.9,15,16

A skin biopsy is not typically required for diagnosis, as MDA5 dermatomyositis has a distinctive cutaneous phenotype. If a biopsy is done, the findings can vary based on the location of the tissue sample. For example, distinctive vacuolar interface dermatitis is observed in regions with the typical dermatomyositis rash.17 Conversely, vasculopathic lesions such as skin ulcers and palmar papules show medium-sized vessel involvement, with intravascular thrombosis and necrosis, which can be pauci-inflammatory or display overt mononuclear vessel wall infiltration.15,17

Myopathy

The myopathic form of MDA5 dermatomyositis is characterized by proximal muscle weakness, elevated muscle enzymes, and abnormalities on electromyography or muscle biopsy.9 However, clinically amyopathic dermatomyositis is defined as the presence of only cutaneous manifestations for at least 6 months without clinical evidence of muscle weakness.9

Notably, not all patients with clinically amyopathic dermatomyositis test positive for anti-MDA5 antibodies. The prevalence of anti-MDA5 antibodies in patients with clinically amyopathic dermatomyositis can range from 23% to 100%.9 On the other hand, the prevalence of clinically amyopathic dermatomyositis in patients with MDA5 dermatomyositis also varies (17% to 100%).9 While clinically amyopathic dermatomyositis was initially described in Japanese patients with MDA5 dermatomyositis,4 individuals in other regions, including the United States, often exhibit significant muscle involvement.7,18

Pulmonary disease

The poor prognosis of MDA5 dermatomyositis is due to its strong association with rapidly progressive ILD. Chest radiography may show lower-lobe reticular or ground-glass opacities (Figure 2A); in patients with rapidly progressive ILD, radiography can show consolidation or, rarely, pneumomediastinum or emphysema. Thoracic high-resolution CT typically reveals consolidation, ground-glass attenuation in the lower zones or in a random pattern, and the absence of intralobular reticular opacities (Figure 2B).19

A 54-year-old woman with melanoma differentiation–associated gene 5 dermatomyositis. (A) Chest radiograph shows diffuse airspace opacities. (B) Thoracic high-resolution computed tomography shows patchy and confluent reticular opacities with underlying confluent areas of ground glass and consolidative opacities with associated architectural distortion, especially at the lung bases. These findings are consistent with organizing pneumonia. There is no pleural effusion or pleural thickening.
Figure 2

A 54-year-old woman with melanoma differentiation–associated gene 5 dermatomyositis. (A) Chest radiograph shows diffuse airspace opacities. (B) Thoracic high-resolution computed tomography shows patchy and confluent reticular opacities with underlying confluent areas of ground glass and consolidative opacities with associated architectural distortion, especially at the lung bases. These findings are consistent with organizing pneumonia. There is no pleural effusion or pleural thickening.

The prevalence of rapidly progressive ILD in patients with MDA5 dermatomyositis varies by region. In Japan and East Asia, ILD affects 82% to 100% of patients with MDA5 dermatomyositis, of whom 39% to 100% have rapidly progressive ILD.9 In contrast, among White patients, ILD occurs in 38% to 73% and rapidly progressive ILD in 20% to 57%.9

Patients with MDA5 dermatomyositis may present with ILD as the first and only symptom, never develop ILD throughout the disease course, or develop characteristic skin lesions months after disease onset.9 Patients who develop rapidly progressive ILD have an estimated mortality rate of 50%, and death occurs most often in the very early stages of the disease course.9,12,20 Pulmonary disease progression tends to slow down 6 months after onset, and relapses are rare.9 However, recurrences, including severe respiratory or cutaneous relapses, can occur years after onset and months after remission, highlighting the need for new treatments to manage exacerbations.9 Therefore, continuous monitoring for pulmonary deterioration is crucial throughout the course of the illness.

Surgical lung biopsy frequently identifies diffuse alveolar damage, particularly in patients with rapidly progressive ILD.21 Thickened alveolar septa, hyaline membrane formation, and interstitial edema are common. Characteristic features of diffuse alveolar damage also include membranous organization with alveolar occlusion, alveolar duct dilation, and collapsed alveoli.21

Joint inflammation

Studies have reported a high prevalence (42%–82%) of inflammatory arthritis in patients with MDA5 dermatomyositis.12,14,15 Symmetric involvement of small joints of the hands, wrists, and ankles, with significant morning stiffness, is typical.9 Earlier studies showed that some patients tested positive for rheumatoid factor, but none had anti–cyclic citrullinated peptide antibodies.9

Conventional radiography usually shows no bony erosions, but rare erosions have been observed on magnetic resonance imaging.9

No association with malignancy

A large retrospective study showed no clear link between MDA5 dermatomyositis and malignancy, unlike dermatomyositis associated with anti–transcriptional intermediary factor 1 gamma and anti–nuclear matrix protein 2 antibodies, which have been linked with malignancy.12 The few reported cancer cases might be coincidental rather than indicative of a causal (paraneoplastic) relationship.9

THREE CLINICALLY DISTINCT FORMS

It remains unclear why some patients with MDA5 dermatomyositis develop rapidly progressive ILD while others do not. Additionally, it is uncertain whether there are reliable ways to identify those at risk of developing rapidly progressive ILD early in the disease course. In an attempt to better identify patients at risk of developing rapidly progressive ILD, a group in France studied 83 patients with MDA5 dermatomyositis, uncovered various features and outcomes, and classified the disease into the following 3 clinical subtypes.14

  • The rapidly progressive ILD cluster (18.1%) mainly included women with rapidly progressive ILD and mechanic’s hands, and had the highest mortality rate (80%).

  • The rheumatic cluster (55.4%) predominantly included women who mostly experienced arthralgia or inflammatory arthritis (83%), had a lower incidence of rapidly progressive ILD (17%), and had a better overall prognosis.

  • The vasculopathic cluster (26.5%) primarily included men and was characterized by manifestations of skin vasculopathy: Raynaud phenomenon (82%), skin ulcers (77%), digital necrosis (32%), and calcinosis (23%). Proximal myopathy was common (68%), while rapidly progressive ILD was less frequent (23%). The prognosis for this group was intermediate.

A Spanish group previously proposed a similar classification system for predicting outcomes in patients with MDA5 dermatomyositis.16 A subsequent Chinese study identified 3 distinct clinical clusters with varying outcomes, suggesting potential geographic differences in phenotype distribution.22 Rapidly progressive ILD was mostly seen in patients older than 55 years (77.3%); these patients typically presented with fever and elevated inflammatory markers and serum ferritin, and had a poor prognosis. These findings suggest that rapidly progressive ILD may be more frequent in older Asian patients than in European patients.

Although these studies offer valuable insights, it is important to recognize that while demographic, clinical, and thoracic high-resolution CT features may help identify MDA5 dermatomyositis subgroups, accurately predicting long-term outcomes in clinical practice remains challenging due to considerable individual variability and the small cohorts in the above studies.14,16,22

MDA5 ANTIBODY–ASSOCIATED JUVENILE DERMATOMYOSITIS

Juvenile MDA5 dermatomyositis is more prevalent in Japanese cohorts and is characterized by constitutional symptoms and relatively mild muscle involvement compared with other types of juvenile dermatomyositis.9 Like the adult form of MDA5 dermatomyositis, palmar papules, skin ulcerations, and inflammatory arthritis are features of juvenile MDA5 dermatomyositis. There is also an increased risk of ILD; however, the association between juvenile MDA5 dermatomyositis and rapidly progressive ILD is debated, with studies reporting conflicting data on rapidly progressive ILD frequency and outcomes.9

SHARED FEATURES BETWEEN MDA5 DERMATOMYOSITIS AND COVID-19

Patients with COVID-19 can develop interstitial pneumonia that resembles MDA5 dermatomyositis– associated ILD.9 Therefore, in patients with rapidly progressive ILD who test negative for severe acute respiratory syndrome coronavirus 2 by reverse transcription polymerase chain reaction or equivalent methods, it is crucial to carefully evaluate for MDA5 dermatomyositis.9

Interestingly, several recent studies suggested that there has been an upsurge in MDA5 dermatomyositis after the COVID-19 pandemic, possibly due to shared autoimmune mechanisms.23 Both conditions involve type I interferon activation; however, early interferon response in COVID-19 aids viral defense.9 Like MDA5 dermatomyositis, COVID-19 also causes endothelial damage and thrombosis, marked by enhanced endothelial and platelet activation, elevated serum coagulation factors, and fibrinolytic enzymes. MDA5 can also localize to immune cell surfaces, triggering persistent activation of the type I interferon pathway and immune-mediated cytotoxicity, similar to COVID-19. Nonetheless, it should also be noted that viral infections can potentially induce transient, low-titer, polyspecific autoantibodies, including anti-MDA5 antibodies.9

DIFFERENTIAL DIAGNOSIS

When the classic rash and ILD are not present, MDA5 dermatomyositis can be misdiagnosed as rheumatoid arthritis because it causes symmetrical inflammatory arthritis affecting the small joints of the hands, wrists, and ankles, and patients may have a positive rheumatoid factor (but no anti–cyclic citrullinated peptide antibodies), as discussed earlier.9

Some patients initially present with a psoriasiform dermatitis and inflammatory arthritis, without muscle weakness (clinically amyopathic dermatomyositis) or ILD, which may be misdiagnosed as psoriatic arthritis if screening for anti-MDA5 antibodies is not performed.9

Furthermore, some patients present with a phenotype that resembles antisynthetase syndrome (fever, arthritis, Raynaud phenomenon, mechanic’s hands, and ILD), adding to diagnostic challenges.7,9 However, compared with MDA5 dermatomyositis, ILD in antisynthetase syndrome generally tends to be more chronic and responds to steroid therapy, though relapses are not uncommon with tapering. Distinguishing between the 2 is important for guiding treatment and determining prognosis—ILD in MDA5 dermatomyositis often needs early, aggressive immunosuppressive therapy, while a more gradual approach may suffice in antisynthetase syndrome–associated ILD.

TREATMENT

Treating patients with MDA5 dermatomyositis requires a comprehensive, multifaceted approach. Most therapeutic trials have concentrated on rapidly progressive ILD because it is often fatal. There are limited data on mucocutaneous disease, inflammatory arthritis, or myositis, and treatments are frequently based on approaches used for other types of inflammatory arthritis or myositis. However, many rapidly progressive ILD therapies also help address cutaneous manifestations, arthritis, and muscle disease, providing potential benefits across multiple organ systems.

ILD and rapidly progressive ILD

Immunosuppressive therapy. Starting combination immunosuppressive therapy early is widely recommended and is associated with improved outcomes. Most studies support using glucocorticoids, a calcineurin inhibitor (cyclosporine or tacrolimus), and mycophenolate mofetil or intravenous cyclophosphamide—often called triple therapy.24,25 Emerging data suggest early combination induction therapy may improve survival in rapidly progressive ILD compared with sequential or step-up approaches.24,25 Risks of these intensive regimens include opportunistic infections (eg, cytomegalovirus reactivation, Pneumocystis jirovecii pneumonia) and renal toxicity, particularly from calcineurin inhibitors.25 However, despite aggressive treatment, overall mortality remains high (up to 40%), and many patients develop refractory disease, often indicated by increasing ferritin levels.9

The monoclonal antibody rituximab has been used in refractory cases because it depletes B cells and targets the proposed pathogenic role of anti-MDA5 antibodies, although more extensive studies are needed to validate its efficacy.9,26

Janus kinase inhibitors such as tofacitinib and ruxolitinib target the type I interferon pathway central to MDA5 dermatomyositis pathogenesis and have shown efficacy in refractory ILD.9,27 A Japanese clinical trial reported 100% 6-month survival in patients treated with tofacitinib plus glucocorticoids vs 78% with standard therapy, suggesting they may be a valuable first-line therapy.28 However, obtaining insurance approval for off-label use of Janus kinase inhibitors in MDA5 dermatomyositis can be challenging. Moreover, high viral reactivation rates (cytomegalovirus 100%, varicellazoster virus 60%) and bacterial infections (80%) necessitate careful patient selection and prophylaxis.27

Intravenous immunoglobulin and plasmapheresis (plasma exchange) have been used in refractory or rapidly progressive ILD. Intravenous immunoglobulin may help in the myositis-predominant phenotype via immunomodulation,29 while plasmapheresis aims to remove circulating anti-MDA5 antibodies.30 However, robust evidence supporting either intervention remains limited.

Antifibrotics like nintedanib and pirfenidone show promise in treating ILD beyond idiopathic pulmonary fibrosis. A retrospective study of patients with MDA5 dermatomyositis reported improved symptoms, thoracic high-resolution CT score, and survival with nintedanib, which was generally well tolerated despite reports of frequent diarrhea.31 Larger-scale randomized trials are necessary to clarify the role of antifibrotics.

Lung transplantation is a potential option for MDA5 dermatomyositis–associated rapidly progressive ILD when intensive immunosuppressive regimens fail.24,32 Case reports and series suggest promising outcomes, and most patients are successfully discharged after transplant.8,33 However, anti-MDA5 antibody levels may influence success, and their downtrend or clearance before transplant is critical to reduce complications like dermatomyositis flares or recurrent rapidly progressive ILD.33 Careful patient selection is key to optimizing outcomes.

Extracorporeal membrane oxygenation can be considered in critical situations as a temporary measure while awaiting a clinical response or as a bridge to lung transplantation.32,33

Cutaneous lesions

In addition to glucocorticoids, various immunosuppressants are used to treat skin lesions. Rituximab is effective, even for refractory cases.26 Intravenous immunoglobulin has also been beneficial, especially for palmar lesions and persistent oral ulcers.29,34 High-dose glucocorticoids with tacrolimus or cyclophosphamide are often used in severe cases.35 Tofacitinib has shown success in both adults and children, promoting healing of skin ulcers and other cutaneous lesions.36,37

Despite limited outcome data on intensive immunosuppressive therapy for cutaneous lesions, some case reports have described treatment resistance.9,25 Given that vascular injury plays a central role in the development of skin lesions, adding sildenafil (a phosphodiesterase inhibitor),38 botulinum toxin,39 or bosentan (an endothelin receptor antagonist)39,40 to immunosuppressive therapy may help with managing recalcitrant skin ulcerations.

Inflammatory arthritis

Without randomized studies, inflammatory arthritis in MDA5 dermatomyositis is treated by extrapolating from rheumatoid arthritis, starting with glucocorticoids. Methotrexate, hydroxychloroquine, or leflunomide are often added for long-term management of inflammatory arthritis, though supporting evidence is limited. Biologics, including anakinra (an interleukin-1 receptor antagonist), have shown promise in refractory cases.41 Tofacitinib is also effective in managing inflammatory arthritis.37

Myositis

Immunosuppression is the mainstay of therapy. High-dose glucocorticoids (eg, prednisone 1 mg/kg daily) is first-line treatment, which is then tapered based on the patient’s clinical response.42 In cases of rapidly worsening disease, intravenous methylprednisolone 1,000 mg daily for 3 to 5 days may be used initially before transitioning to oral glucocorticoids.42 Second-line agents— methotrexate, azathioprine, mycophenolate mofetil, or tacrolimus—are often added for their steroid-sparing effects.42 Intravenous immunoglobulin 2 g/kg over 2 to 5 days, every 4 weeks, is effective in glucocorticoid-refractory cases.24,42 Tofacitinib is potentially effective in newly diagnosed patients who have not started treatment.37

PROPHYLACTIC MEASURES

Given the significant risk of opportunistic infections from intense immunosuppressive therapy, appropriate immunizations should be completed whenever possible before starting MDA5 dermatomyositis treatment. Prophylactic trimethoprim-sulfamethoxazole is also advised to lower the risk of Pneumocystis jirovecii pneumonia.24,43

Patients taking long-term glucocorticoids can develop osteoporosis.24 Strategies to prevent bone loss and reduce fracture risk include adequate calcium and vitamin D intake. Patients who have osteoporosis or significant fracture risk should be started on a bisphosphonate.44 For patients who develop glucocorticoid-induced osteoporosis, treatment should be started early based on risk assessment.

Table 1 lists practical strategies for early detection and diagnosis of MDA5 dermatomyositis, and Figure 3 highlights treatment approaches for combination therapy, infection prevention, and severity-based interventions.

View this table:
TABLE 1

Diagnosing melanoma differentiation–associated gene 5 (MDA5) dermatomyositis

Management of melanoma differentiation–associated gene 5 (MDA5) dermatomyositis, emphasizing combination therapy, opportunistic infection prophylaxis, and tailored interventions based on severity. Based on information from references 9, 24–27, and 29–44.
Figure 3

Management of melanoma differentiation–associated gene 5 (MDA5) dermatomyositis, emphasizing combination therapy, opportunistic infection prophylaxis, and tailored interventions based on severity.

Based on information from references 9, 24–27, and 29–44.

PROGNOSIS

The prognosis is often grim for patients with rapidly progressive ILD. In many patients, the disease remains resistant to treatment. The overall mortality rate is 40%, rising to 50% in patients with rapidly progressive ILD.9,32 Elevated serum ferritin levels and anti-Ro52 positivity are associated with worse outcomes.43 Early aggressive immunosuppressive therapy and timely lung transplantation can be lifesaving in severe cases.6,8

CONCLUSION

MDA5 dermatomyositis represents a distinct subset of idiopathic inflammatory myopathy with unique clinical phenotypes and significant challenges in diagnosis and management. The systemic nature of the disease, characterized by hallmark skin manifestations, variable muscle involvement, and life-threatening rapidly progressive ILD, underscores the need for early recognition and aggressive immunosuppressive therapy. Despite advancements in diagnostic assays and therapeutic strategies, the high mortality rates associated with rapidly progressive ILD and treatment-resistant cases highlight the critical need for continued research into the pathogenesis, prognostic markers, and novel targeted therapies for this devastating disease. Multidisciplinary care, incorporating dermatologic, pulmonary, and rheumatologic expertise, remains essential for optimizing outcomes in this complex and heterogeneous disorder.

DISCLOSURES

Dr. Chatterjee reports no relevant financial relationships which, in the context of their contributions, could be perceived as a potential conflict of interest.

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