IDO1 and carcinoma: IDO1-positive carcinomas (n = 90): The histotypes were tubular (n = 59; 66%), cystic (n = 10; 11%), solid (n = 9; 10%), papillary (n = 5; 6%), tubular and solid (n = 3; 3%), tubulopapillary (n = 2; 2%), and tubular and cystic (n = 2; 2%).