Cytology of pulmonary adenocarcinomas showing enteric differentiation

OBJECTIVE: To evaluate cytologic differences between primary pulmonary adenocarcinomas showing enteric differentiation (PAED) primary pulmonary adenocarcinomas of ordinary structure (PAC) and pulmonary metastases from colorectal carcinomas (MCR). STUDY DESIGN: During an 18-year period (1986-2003), cytologic materials were obtained from 5 PAEDs confirmed by pathologic examination of surgically resected specimens at the Cancer Institute Hospital. Aspiration cytologic and/or imprint smears of routine samples stained by the Papanicolaou method from the PAED cases were reviewed in comparison with 10 cases each of PAC showing a tubular pattern and MCR. RESULTS: The aspiration biopsy cytology and imprints showed similar features. Abundant necrotic debris in the background was recognized in a majority of all cases independent of the group. None to slight overlapping of tumor cells and less frequent palisading or glandular arrangements were characteristic features of PAED, significantly differing from MCR. Moreover, differences in nuclear features were evident as follows: in the MCR group, nuclear chromatin was hyperchromatic and coarsely condensed, and there were prominent nucleoli, whereas a slightly hyperchromatic pattern with some small to enlarged nucleoli was typical of PAED and PAC cases. CONCLUSION: Although diagnosis of PAED by routine cytology is difficult due to the features of the lesion, differential diagnosis between PAED, PAC and MCR is a possible using conventional cytologic criteria.