Pattern Recognition in Thyroid and Lung Disease

Explanation: As per the new pathology classification of adenocarcinomas of the lung (reference by Travis et al below) the term bronchioloalveolar cell carcinoma (BAC) has been eliminated and has been replaced with “carcinoma in situ”, a pre-invasive lesion, therefore A is incorrect. Atypical adenomatous hyperplasia (AAH), another pre-invasive lesion, appears as a pure groundglass nodule without a solid component, therefore B is incorrect. A groundglass nodule with a small solid component (<5mm) is most likely due to “minimally invasive adenocarcinoma” (possibly carcinoma in situ). Thus the best answer is C. These lesions have an excellent prognosis with a 100% 5-year survival following resection. Subsolid nodules with larger solid components than this nodule are more likely to represent invasive adenocarcinomas, therefore D is incorrect.