Task: Translation
Input (English): A 58-year-old woman with a history of Riedel's thyroiditis. He has abdominal pain, weight loss and obstructive jaundice. In view of the radiological suspicion of pancreatic carcinoma, a cephalic duodenopancreatectomy is performed. In the anatomopathological study we did not find a carcinoma, but abundant inflammatory cells with a tendency to surround ducts, marked fibrosis, obliterating phlebitis and more than 50 IgG4 + plasma cells per high-power field. Which is the diagnosis?
Output (Spanish): Mujer de 58 años con antecedente de tiroiditis de Riedel. Presenta dolor abdominal, pérdida de peso e ictericia obstructiva. Ante la sospecha radiológica de carcinoma de páncreas, se realiza una duodenopancreatectomía cefálica. En el estudio anatomopatológico no encontramos un carcinoma, sino abundantes células inflamatorias con tendencia a rodear ductos, marcada fibrosis, flebitis obliterante y más de 50 células plasmáticas IgG4+ por campo de gran aumento. ¿Cuál es el diagnóstico?