Fallibility of transthoracic needle biopsy of anterior mediastinal masses.

Percutaneous transthoracic core needle biopsy has been advocated as a highly accurate technique for the diagnosis of anterior mediastinal masses. A patient is described with a large anterior mediastinal mass in whom the diagnosis of mediastinal carcinoid tumour was made by transthoracic core needle biopsy. At definitive surgical resection the tumour proved to be a B cell lymphoma. This case illustrates one of the important limitations of needle biopsy with its potential for sampling error.