The radiologically detectable pulmonary involvement of NHL at diagnosis is about 4%. The commonest intrathoracic manifestations of secondary pulmonary lymphoma are mediastinal or hilar lymph node enlargement. And the most frequent manifestations of pulmonary parenchymal lymphoma are lymphomatous nodules. But, when patients with newly diagnosed lymphoma exhibit rapidly progressive parenchymal lesions, an infection, such as pneumonia, is usually suspected. We present a report of a patient who developed rapidly progressive pulmonary involvement with T cell lymphoma, which was considered to be pneumonia bacause of high fever and rapidly progressive radiologic findings.