Primary Pulmonary Pseudolymphoma

Primary pulmonary pseudolymphoma is a benign lesion of the lung parenchyma, characterized histologically by the presence of true lymphoid germinal centers in a massive infiltrate of well differentiated lymphocytes and other inflammatory cells. For purposes of therapy and prognosis it is important to distinguish this lesion from primary pulmonary malignant lymphoma. This report correlates the clinical and pathological observations with the radiological findings in 10 cases of primary pulmonary pseudolymphoma seen during the years 1948 to 1962, 6 from the Barnes Hospital Group, and 4 in consultation. The authors previously reported 9 of the 10 cases in a review of lymphomatous tumors of the lung, but the radiological findings were not described (7). Clinical Findings The 10 patients ranged in age from thirty-eight to eighty, with an average of 56.3 years. There were 5 men and 5 women, all Caucasian. In 7 the lesions were detected in routine radiographic examinations of the chest, and the patients were completely asymptomatic. Mild pleuritic pain, shoulder ache, and fatigue of six to fourteen months duration prompted initial chest radiographs in the remaining 3 cases. Physical examination was normal in all patients; none had peripheral adenopathy, hepatomegaly, splenomegaly, or osteoarthropathy. All laboratory tests performed, including total and differential white blood counts, resulted in normal findings, except for 3 patients with hemoglobin values greater than 15 gm. per cent. These values were 15.5, 15.9, and 17.3 gm. per cent. Bronchoscopy was performed in 8 patients and findings were normal in all. Sputum cytology and bronchial washings were normal in 6. In 2 cases they were initially reported as showing undifferentiated carcinoma because the cells in the sputum suggested small-cell carcinoma and the pathologist knew there was a mass in the lung. Radiological Findings Eight lesions were consolidated pulmonary parenchymal infiltrates. Five of the 8 were limited to a pulmonary segment or lobe, and 3 involved two adjacent lobes. Seven originated close to the hilus and extended toward the lung periphery; 1 arose distal to the hilus and was limited to the posterior basilar segment of the right lower lobe. Only 1 of the 8 infiltrations reached the pleura along the lateral chest wall (Fig. 1, Case II), but most of them abutted a mediastinal pleural reflection or interlobar fissure. Only 1 was associated with atelectasis, and in this case the atelectasis was marked, involving the entire right lower lobe (Fig. 2, Case III). The central portion of some of the infiltrations was extremely dense. All lesions tended to become fainter peripherally, and their margins were irregular and indistinct.