Sclerosing pneumocytoma accompanied with dilated air-containing space.

Sclerosing pneumocytomas are one of the most common benign lung tumors. Although rare [1–4], some of them can be accompanied by dilated air-containing space. A 61-year-old woman was referred to our hospital because of a nodule in the left lung detected in a chest radiograph mass screening program (Figure 1A). Chest computed tomography (CT) showed a well demarcated nodule with a peritumoral air-lucent zone in the lower left lobe. In chest radiograph taken at another medical institution 7 years ago, a nodule was detected in the left lung, which was diagnosed as a sclerosing pneumocytoma (Figure 1B). However, the patient did not wish further evaluation because she was asymptomatic. Eighteen months after the first visit to our hospital, she came to our institution because of hemoptysis. Chest CT taken at that time confirmed that the nodule with peritumoral air-lucent zone increased by a maximum diameter of 7 mm at this interval (Figure 1C). With the advent of hemoptysis, surgical resection was perfor-med. The patient was pathologically diagnosed as having a sclerosing pneumocytoma, and the presence of a dilated air-containing space corresponding to the peritumoral air-lucent zone seen on CT was pathologically confirmed. When calculated using Schwartz’s formula, the tumor doubling time was 5.9 years, and its onset was estimated to be more than 10 years ago.