A case of primary pulmonary non-Hodgkin's lymphoma showing a fine granular pattern around the main tumor on thin-slice CT

A 61-year-old woman was admitted for evaluation of an abnormal shadow found incidentally on a chest radiograph. A 35 x 20 mm nodule with an ill-defined margin was found at the left hilum on conventional CT. Thin-slice (2 mm) CT was done, and a fine granular zone was found around the lesion. Left upper lobectomy was done and the lesion proved to be a primary pulmonary non-Hodgkin's lymphoma (small cell type, B-cell). The granular pattern seen on CT was found to correspond to intraseptal micronodules scattered along the lymphatic vessels, a finding which is considered to be pathognomonic of pulmonary lymphomas by many pathologists. We know of no previous description of how these histologic characteristics can appear on high-resolution thin-slice CT. These findings will be helpful for the CT diagnosis of pulmonary lymphoma.