Transthoracic needle aspiration biopsy in inflammatory pseudotumors of the lung

The cytologic findings on transthoracic needle aspiration biopsy in four patients with pulmonary inflammatory pseudotumor are described. These findings have not been previously illustrated in the literature. The main cytologic components of this lesion are histiocytes, lymphocytes, fibroblasts, pneumocytes, and plasma cells. Familiarity with these features is essential to avoid misdiagnosis and possible overtreatment.