tokens: Atrial fibrillation following chemotherapy for stage IIIE diffuse large B - cell gastric lymphoma in a patient with myotonic dystrophy ( Steinert's disease ). The authors describe the unusual association between diffuse B - cell gastric lymphoma and myotonic dystrophy , the most common form of adult muscular dystrophy , and sudden atrial fibrillation following one cycle of doxorubicin - based chemotherapy in the same patient .