Lung fibrosis and painful fingers

Abstract

A 38-year-old man with no previous medical illness presented with 2-month history of dry cough and dyspnoea. There was no hemoptysis or fever. He was a non-smoker. Of note, he started to have burning sensation and rashes over his fingers for the past 6 months. Clinically, he was hypoxic and required high oxygen supplementation. Respiratory examination revealed fine crackles in both lung bases. Cutaneous assessment revealed palmar papules and digital ulcers in all his fingers. [Fig. 1, Panel A] There were also faint erythematous rashes around his eyelids. Peripheral pulses and sensory examination were normal. Blood investigations for complete blood count, cryoglobulins, creatine kinase, extractable nuclear antigen and anti-neutrophilic cytoplasmic autoantibody were normal. Anti-nuclear antibody was positive at a titre of 1:640, speckled pattern. Computed tomography of the thorax showed non-specific interstitial pneumonitis. [Fig. 1, Panel B] What is the diagnosis? A diagnosis of clinically amyopathic dermatomyositis (CADM) with rapidly progressive interstitial lung disease was made. Anti-melanoma differentiation-associated gene 5 (anti-MDA5) antibody was detected strongly positive later. Dermatomyositis (DM) typically manifests as inflammatory myopathy with cutaneous features. There are, however, patients who present with muscle weakness without typical skin changes or vice versa. In recent years, the recognition of DM-specific autoantibody has greatly improved the clinical diagnosis and phenotypic classification. Most patients with anti-MDA5-associated DM are hypomyopathic or amyopathic. They often develop skin ulcers and necrosis on the palmar surface of the fingers and palms. The presence of anti-MDA5 antibody is also associated with interstitial lung disease that is highly lethal. A Japanese study reported that 46% of patients died of respiratory failure within 6 months of disease onset [[1]Nakashima R Imura Y Kobayashi S Yukawa N Yoshifuji H Nojima T et al.The RIG-I-like receptor IFIH1/MDA5 is a dermatomyositis-specific autoantigen identified by the anti-CADM-140 antibody.Rheumatology. 2009; 49: 433-440Crossref PubMed Scopus (241) Google Scholar]. As the disease is aggressive, an intensified immunotherapy regime consisting of glucocorticoids and a second-line agent (cyclophosphamide, rituximab or tacrolimus) should be initiated in patients with progressive lung disease [[2]Selva-O’Callaghan A Pinal-Fernandez I Trallero-Araguas E Milisenda JC Grau-Junyent JM Mammen AL Classification and management of adult inflammatory myopathies.Lancet Neurol. 2018; 17: 816-828Abstract Full Text Full Text PDF PubMed Scopus (171) Google Scholar]. An early diagnosis with high clinical suspicion is of paramount importance to treatment success. None.