[Amyopathic dermatomyositis (DM) with anti-MDA5 antibodies, associated with bullous pemphigoid, Sjögren syndrome and gastric MALT lymphoma]

Background: The inflammatory myopathies are a heterogeneous group of muscle diseases and comprise polymyositis, dermatomyositis (DM), myopathies associated with cancers, necrotising myositis and inclusion body myositis. DM occasionally exhibits few or no muscular signs: i.e. hypomyopathic/amyopathic DM. Anti-MDA5 dermatomyositis (DM) is a rare form of dermatomyositis that is frequently amyopathic; the prognosis is linked mainly to pulmonary involvement.

Patients and methods: A 69-year-old woman treated for mucosa-associated lymphoid tissue (MALT) gastric lymphoma was referred for a bullous eruption. Based on the investigations performed, a diagnosis was made of bullous pemphigoid. At the same time, amyopathic dermatomyositis was discovered together with interstitial lung disease. Systemic steroids were introduced in combination with rituximab. A favourable outcome was achieved.

Discussion: Anti-MDA5 dermatomyositis must be considered systematically in all cases of pulmonary involvement associated with cutaneous signs of dermatomyositis, in which no muscular involvement is generally seen. This condition accounts for up to 7% of DM and carries a severe prognosis due to pulmonary involvement.