Two different adenocarcinomas. Comprehensive histologic review of case 12 (paraffin-embedded, formalin-fixed tissues, hematoxylin and eosin staining). The following morphological subtypes are identified in tumor A (panel A1, x40): 70% papillary (panel A2, x200) and 30% acinar with clear cell features (panel A3, x200). The following morphological subtypes are identified in tumor B (panel B1, x40): 60% acinar (panel B2, x200) and 40% papillary with abundant extracellular mucin. These different morphological features suggest these tumors are multiple primary lung cancer.