Discussion
Diagnosis With Brief Discussion
- Diagnosis
- MDA-5 associated ILD
- Radiologic Findings
- Fig 1. Serial chest radiographs show progressive subpleural reticulation and ground glass opacities in both lungs.
Fig 2. Initial chest CT scan shows mild subpleural GGO and consolidation in both lungs with mild basal lung predominancy.
Fig 3. Follow-up chest CT scan after 2 months shows rapidly progressed subpleural GGO and consolidations in both lungs.
- Brief Review
- The patient had no past history and visited the emergency room with acute dyspnea. Her ROS and physical exam showed xerostomia and skin rash for 2 months. However, her serum antibody tests showed negative for common autoimmune antibodies. Her initial chest radiograph and chest CT scan showed subpleural GGO and consolidation with mild basal lung predominance, and these findings are suspicious for interstitial lung disease such as organizing pneumonia or nonspecific interstitial pneumonia (NSIP). After 2months later, her follow-up chest CT scan revealed rapidly progressed interstitial lung disease with organizing pneumonia pattern. With the clinician’s suspicion, a myositis panel study was done, and the MDA-5 antibody (Ab) was positive.
The anti-MDA5 Ab was initially called the anti-CADM-140 Ab since it was first found in patients with clinically asymptomatic dermatomyositis (CADM). It was renamed after MDA5 was found to be the corresponding antigen. Patients who are positive for Anti-MDA5 Ab usually present with a rapidly progressive acute to subacute course of the disease, and often present to the emergency department with severe dyspnea. The prognosis of Anti-MDA5 Ab-positive patients is determined by the ability to save the patient in the early stages of the disease. When the patient presents with rapidly progressive ILD, a diagnosis of dermatomyositis may not be possible to make clinically. Notably, the indication of Anti-MDA5 Ab positivity based on imaging findings may be lifesaving.
The image findings of Anti-MDA5 Ab ILD are 1) Acute or subacute onset, often rapidly progressive; 2) Severe organizing pneumonia pattern leading to DAD, but without chronic lesions; 3) Diffuse, or lower lobe predominant consolidation/GGO, or both; 4) Ground glass attenuation was more frequent and craniocaudal distribution was more extensive in Anti-MDA5 Ab positive group. More aggressive treatment and careful follow-up are desirable when CT shows extensive lesions, multiple GGOs with random distribution, and a typical diffuse alveolar damage (DAD) pattern.
- References
- 1. Mariampillai K, Granger B, Amelin D, Guiguet M, Hachulla E, Maurier F, et al. Development of a new classification system for idiopathic inflammatory myopathies based on clinical manifestations and myositis-specific autoantibodies. JAMA neurology. 2018;75(12):1528-37.
2. Egashira R. High-Resolution CT Findings of Myositis-Related Interstitial Lung Disease. Medicina. 2021;57(7):692.
3. Laporte A, Mariampillai K, Allenbach Y, Pasi N, Donciu V, Toledano D, et al. Idiopathic inflammatory myopathies: CT characteristics of interstitial lung disease and their association (s) with myositis-specific autoantibodies. European Radiology. 2022;32(5):3480-9.
- Keywords