This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
[{'content': "Histopathology of a lung cancer shows 'Clara cells' probable diagnosis is - \nSelect and explain. \nA. Squamous cell cancer, B. Bronchio alveolar cancer, C. Large cell cancer, D. Papillary carcinoma", 'role': 'user'}, {'content': 'Answer: B \nExplanation: Bronchioloalveolar carcinoma \n\nIt is a histological type of adenocarcinoma.\nIt occurs in the pulmonary parenchyma in the terminal bronchioloalveolar pattern.\nThe tumor is almost always in the peripheral portion of the lung.\nMore often it occurs as multiple diffuse nodules that sometimes coalesce to produce a pneumonia-like consolidation.\nThe key feature of bronchioloalveolar carcinomas is their growth along preexisting structures without destruction of the alveolar architecture. This growth pattern has been termed "lepidic" an allusion to the neoplastic cells resembling butterflies sitting on a fence.\nStromal, vascular or pleural invasion is characteristically absent.\nBronchioloalveolar carcinoma consists of mucin-secreting bronchiolar cells, Clara cells, or rarely type II pneumocytes.\nThese tend to have aerogenous spread and patient usually dies of suffocation (not by metastatic spread).\nBronchioloalveolar carcinoma has two subtypes -\n\ni)\xa0Non-mucinous\xa0→ Rare aerogenous spread and therefore amenable to surgical resection.\nii)\xa0Mucinous\xa0→\xa0Tend to spread aerogenously, forming satellite tumors.', 'role': 'assistant'}]