[Nodular lymphoid hyperplasia - a rare case of lymphoproliferative disorder of the lungs].

Nodular lymphoid hyperplasia (NLH) belongs to a very rare, mild, lymphoproliferative disease of unestablished aetiology historically included in the group of pseudolymphomas. Its existence was controversial for many years, until modern techniques of pathomorphological diagnosis approved it as a separate entity of lung disease. It manifests in the form of well limited nodules localized in the lungs, which are mostly identified accidentally. Clinical symptoms are rare and nonspecific; the disease usually occupies only one lung. Pathomorphological diagnosis requires immunohistochemical designation of expressions of numerous antigens in order to exclude malignant lymphoma of the lungs. Surgical resection is used in cases of larger nodules; the smaller ones require periodic observation, and the prognosis is good. The authors describe the case of 65-year-old woman with pulmonary nodules which were detected accidentally in the right lung. The patient was qualified for right-sided videothoracoscopy and removal of the lung nodule. In classic HE staining of the histological material, the presence of lymphoid infiltration of the lungs was revealed, which formed lymph follicles with reactive germinal centres. In order to differentiate from the malignant lymphatic expansion, immunohistochemical designations were made, which showed positive expression of CD20 antigen in the B cell zone, positive expression of the CD3 antigen in the T cells zone, positive expression of CD23 antigen in the lymph follicles, negative expression of bcl-2 in the lymph follicles, and positive expression of MIB-1 in the germinal centres of lymph follicles. Such a histopathological and immunohistochemical picture provided the basis for diagnosis of nodular lymphoid hyperplasia of the lung.