Pseudomesotheliomatous presentation of primary signet ring cell carcinoma of lung.

Signet ring cell carcinoma is a unique mucin secreting adenocarcinoma. It generally arises from stomach, colon, rectum or breast and rarely from lung. Pleural membrane involvement is common in lung cancer manifesting as pleural effusion. Rarely, it may encase the whole lung without effusion mimicking mesothelioma and is termed as "pseudomesothelioma". A 35-year-old male presented with a pleural mass encasing the whole of the right lung without any pleural effusion and investigations revealed it to be primary signet ring cell adenocarcinoma of the lung.