Patients and staging. The data from 29 patients with newly diagnosed PPL in the Sun Yat-Sen University Cancer Center in China from January 2001 to December 2008 were retrospectively analyzed. The study protocol was approved by the Institutional Review Board of the Sun Yat-Sen University Cancer Center. All patients consented to have their medical records reviewed for research purposes. The diagnosis of PPL was based on the following criteria [2, 11] : unilateral or bilateral lung involvement of NHL; no history of lymphoma; no evidence of extrathoracic lymphoma at the time of diagnosis by clinical staging workup. No extrathoracic lymphoma was detectable within 3 months after the initial diagnosis. Cases with hilar/mediastinal adenopathy or adjacent chest wall invasion were also included in our study, as described in previous reports [6, 11] . All patients were staged according to the Ann Arbor staging system [22] . IPI scores were also measured [23] .