Imaging features of primary pulmonary lymphomas

Background: Primitive pulmonary lymphomas (PPL) are rare tumors, often misdiagnosed by radiologists.

Methods: In order to illustrate the various radiological presentations of PPL, we report a retrospective series of nine cases of PPL collected in our service over a period of four years. A mucosa-associated lymphoid tissue (MALT) lymphoma was found in six patients, a diffuse large B-cell lymphoma in two patients and lymphomatoid granulomatosis in one patient. All diagnoses were proven histologically by bronchial or surgical biopsies.

Results: Among the six cases of MALT lymphoma, computed tomography (CT) demonstrated one or more areas of alveolar consolidation in four patients, progressing with a chronic course over 2 years in two patients. Other CT features were nodular opacities associated with a mass or consolidation and diffuse "ground glass" opacities. In the two cases of diffuse large B-cell lymphoma, CT showed one or more masses spreading locally, mimicking primary bronchial carcinoma. In lymphomatoid granulomatosis the CT showed diffuse interstitial disease with fibrosis.

Conclusions: The imaging features of PPL are very polymorphic. The diagnosis of MALT lymphoma is often difficult because its radiological appearance is often falsely reassuring.