Dermatomyosite amyopathique avec anticorps anti-MDA-5, associée à une pemphigoïde bulleuse, un syndrome de Sjögren et un lymphome de type MALT

Case Report: Concurrence of Dermatomyositis and Autoimmune Blistering Diseases: Two Case Reports and a Literature Review

Dermatomyositis (DM) is an idiopathic inflammatory myopathy primarily involving skin and muscles. Clinically amyopathic dermatomyositis (CADM), a subset of DM, presents with characteristic cutaneous manifestations without clinical evidence of myositis. Although rare, vesiculobullous eruptions could develop in DM patients. Such “bullous DM” is commonly considered a sign of internal malignancy. However, some cases with similar presentations were diagnosed as autoimmune blistering disease eventually. Herein, we reported two cases of CADM with autoimmune blisters formed. Case 1 presented with vesicles and was diagnosed with CADM initially. However, this patient developed blisters again years later and was diagnosed with “pemphigus foliaceous” (PF) accordingly. Case 2, with a history of nasopharyngeal carcinoma and CADM, developed bullous pemphigoid several days after using a heat patch on her abdomen. The association between disease occurrence and local skin damage might provide more evidence to support the “epitope spreading” hypothesis. Moreover, we reviewed related literature and discussed the differences between the two disease entities in clinical presentations, pathogenesis, therapy, and the risk of complications.

[Severe MDA5 dermatomyositis associated with cancer and controlled by JAK inhibitor]

Dermatomyositis is an idiopathic inflammatory myopathy with various clinical and serological profiles, including poor prognosis forms for which aggressive immunosuppressive treatment is warranted. We report the case of a 60-year-old woman referred to our hospital for an anti-melanoma differentiation-associated 5 gene antibody-positive dermatomyositis (MDA5 DM) with rapidly progressive interstitial pneumonia, typical cutaneous features and muscular impairment. Treatment with high-dose methylprednisolone, cyclophosphamide and gamma globulin was performed, but the patient remained corticodependant. Blood detection of positive interferon signature justified the administration of an anti-JAK1/2, leading to the clinical remission and the regression of the interferon signature. After 12 months of follow up, a small cell carcinoma was discovered, raising the question of a paraneoplastic syndrome, for which the most recent datas are quite reassuring for this kind of MDA5 DM. The presentation of this case is of twofold interest: describing one of the first report of successful treatment of intereronopathy MDA5 DM with ruxolitinib and highlighting an association with a cancer, which is not expected for this phenotype of dermatomyositis.

Dermatomyositis in patients with autoimmune blistering diseases

It is common for multiple autoimmune diseases to occur in the same patient. However, autoimmune blistering diseases (AIBD) do not commonly associate with dermatomyositis (DM). We performed a literature review and found 12 previous reports that may be attributed to misdiagnosis, underreporting, or true rarity of association. Herein, we present a case of pemphigus vulgaris and a case of mucous membrane pemphigoid associated with DM and review the related literature. AIBD-associated interstitial lung disease, genetic predisposition, potential environmental triggers of both AIBD and DM, drug-related triggers, and paraneoplastic processes are discussed. Dermatologists must be vigilant for a second autoimmune disease in patients with AIBD that may have therapeutic implications.