Anti-MDA-5 negative, anti-Ku positive clinically amyopathic dermatomyositis

Dermatol Online J. 2021 Apr 15;27(4):13030/qt1qg7x8gf.

Abstract

We present a patient with anti-MDA5 negative, anti-Ku positive clinically amyopathic dermatomyositis (CADM). A 61-year-old woman presented with a chief complaint of a 20-year history of a pruritic rash that was active on her face, chest, hands, legs, and back. A mildly scaly, erythematous, photo-distributed eruption along with slightly violaceous, scaly papules accentuated on the wrist, metacarpophalangeal joints, proximal interphalangeal and distal interphalangeal joints. Antibody profile was significant for positive ANA and anti-dsDNA, elevated anti-TIF-1gamma (RDL)/p155, and weakly positive anti Ku. Biopsy was consistent with dermatomyositis. Melanoma differentiation-associated gene 5 antibody (anti-MDA-5) has been identified as the most commonly associated autoantibody found in CADM and is associated with poor prognosis and a biomarker for the diagnosis of rapidly progressive interstitial lung disease. To our knowledge, our patient is the first case of negative anti-MDA-5 and anti-Ku positive CADM.

MeSH terms

  • Autoantibodies / blood*
  • Autoimmune Diseases / diagnosis*
  • Dermatomyositis / drug therapy
  • Dermatomyositis / immunology*
  • Dermatomyositis / pathology
  • Female
  • Humans
  • Interferon-Induced Helicase, IFIH1 / immunology*
  • Ku Autoantigen / immunology*
  • Methotrexate / therapeutic use
  • Middle Aged

Substances

  • Autoantibodies
  • IFIH1 protein, human
  • Interferon-Induced Helicase, IFIH1
  • Ku Autoantigen
  • Methotrexate

Supplementary concepts

  • Amyopathic dermatomyositis