[Nonmalignant lymphoid disorders of the chest: a report of 4 cases with a review of literature].

The lung parenchyma, the mediastinal or hilar lymph nodes were involved by several nonmalignant lymphoid disorders which are not specific infections or malignant neoplasm. The etiology of these disorders remains unknown. They may be the outcome of viral-autoimmune causes or some chronic stimulation of the reticuloendothelial system by unknown antigens. Pulmonary pseudolymphoma is a localized pulmonary disease, generally not accompanied by lymph node enlargement or pleural effusion. However, lymph nodes of the mediastinum and hilum are involved in case of giant lymph node hyperplasia and angioimmunoblastic lymphadenopathy. An awareness of the differentiation of these reactive disorders from lymphoma is important because the radiological, clinical and laboratory manifestations may be similar. Final diagnosis must be based on the histological findings, Pulmonary biopsy or lymph node biopsy is always necessary. Adequate amount of biopsied tissue is required for better identification. Immunoperoxidase staining has been proposed to help the study of these conditions.