Texas clinicians report the highly atypical case of a 65-year-old patient initially diagnosed with dermatomyositis on the basis of classic disease criteria:
- the initial picture consisted of a muscle deficit that appeared a few weeks after a rash on the face,
- the work-up revealed hyperCKemia at 4,000 IU/l, positive autoantibodies to Mi2, inflammatory infiltrates and perifascicular atrophy on muscle biopsy,
- the patient also showed signs of peripheral nerve hyperactivity, with involuntary muscle contractions predominating in the upper limbs, and hypertrophy visible to the naked eye,
- EMG abnormalities were also consistent with an additional Isaacs syndrome, but without any biological signature, since anti-potassium channel antibodies, LGI-1 antibodies and CASPR2 antibodies were negative.
According to the authors, this association between two rare pathologies is not fortuitous and could be the result of exacerbated autoimmunity.
