Introduction: Juvenile dermatomyositis does not have, unlike the adult form, a paraneoplastic character.
Exegesis: We report the case of a 12-year-old girl who has a typical dermatomyositis complicated by the appearance of very aggressive lesions of lobular panniculitis predominating in the lower limbs. Their refractory character to different treatments (in particular corticosteroids, chloroquine, dapsone, methotrexate, azathioprine, intravenous immunoglobulins and ciclosporin A) will finally lead to the diagnosis of subcutaneous T-cell lymphoma. This will be complicated by a macrophagic activation syndrome leading to death despite chemotherapy.
Conclusions: The occurrence of panniculitis during a dermatomyositis should lead to the search for a subcutaneous T-cell lymphoma, especially if the lesions are locally aggressive and refractory to usual treatments, which permits an early chemotherapy.