Liver dysfunction in anti-melanoma differentiation-associated gene 5 antibody-positive patients with dermatomyositis

The objective was to investigate the clinical and histological features of liver dysfunction in patients with polymyositis(PM) or dermatomyositis(DM).A total of 115 patients (38 with PM and 77 with DM), who were admitted to our hospital between 2001 and 2012, were retrospectively reviewed. Liver dysfunction was defined as an alanine transaminase(ALT) level ≥ 60 U/l and a disproportionate ALT elevation relative to the creatine kinase level. The histological findings from liver biopsieswere also assessed.The frequencies of liver dysfunction were 3% and 17% in the patients with PM and DM, respectively. Liver dysfunction was not observed in the patients who had malignancies. Among the patients with DM with no malignancies (n = 50), 20% had liver dysfunction, and all of the patients with liver dysfunction were positive for the anti-melanoma differentiation-associatedgene 5 ( MDA5) antibody. Compared with those in the patients who did not have liver dysfunction, the ALT, alkaline phosphatase, γ-glutamyl transferase, and KL-6 levels were significantly elevated in the patients who had liver dysfunction. Six patients, comprising four with DM and two with PM, underwent liver biopsies, and the common histological findings associated with DM were steatosis, hepatocyte ballooning, increases in the pigmented macrophage numbers, and glycogenated nuclei. Hemophagocytosiswas detected in two of three patients with DM who underwent liver biopsiesand bone marrow aspirations. In conclusion, Liver dysfunction might be an extramuscular manifestation in patients with DM who are anti- MDA5antibody-positive. Steatosisand hepatocyte ballooning could be common histological features.