All of the following are features of bronchioalveolar carcinomas lung except:
A. Lepidic spreadB. Some variants carry better prognosis than
adenocarcinomas
C. Mucinous variants are TTF- 1 positive and
CK-20 negative
D. Metastatic adenocarcinomas are TTF-l negative and CK-20 positive
Ans. C. Lepidic spread (spread along surfactant) is the commonest mode of spread of bronchio-alveolar carcinomas, but they have low metastatic potential and lymphatic spread, therefore carry better prognosis as compared to adenocarcinomas. Metastatic adenocarcinomas are differentiated from primary adenocarcinoma by 2 markers, ie, TTF-1 (thyroid transcription factor-1) and CK-20. Primary adenocarcinomas are TTF-l positive and CK-20 negative, the only exception is mucinous variant of bronchioalveolar carcinomas which behave like metastatic adenocarcinomas
