Intracytoplasmic lumina in invasive micropapillary carcinoma of the lung.

Micropapillary carcinoma of the lung is a rare neoplasm, and several reports on micropapillary carcinoma of the lung have been presented to date. We present a case of micropapillary carcinoma of the lung here. A 75-yr-old Japanese man received the medical checkup and his chest X-ray disclosed the abnormal shadow of the lower lobe of the left lung. The histological examination of resected lung and extirpated lymph node showed the finding of micropapillary carcinoma. Some neoplastic cells of primary site contained intracytoplasmic lumina positive for Alcian blue and PAS stains. Pleural effusion appeared 9-mo after the operation. The cytology of pleural effusion showed cohesive clusters of neoplastic cells consisting of 3-20 cells without fibrovascular core. Additionally, intracytoplasmic lumina were observed in some neoplastic cells. Finally, carcinoma cells with micropapillary morphology may possess the intracytoplasmic lumina in the cytoplasm of metastatic site as well as primary site. 2006 Wiley-Liss, Inc.