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We report herein the case of a 59-year-old asymptomatic man who was referred to our department for investigation of an abnormal shadow detected on a routine chest roentogenogram. Computed tomography (CT) showed an infiltrative shadow and air bronchogram in the right middle lobe without mediastinal lymphadenopathy, and a right middle lobectomy was performed with hilar and interlobar lymph node excision. Microscopically, the tumor consisted of small lymphoid cells without atypia, admixed with neutrophils and other mononuclear cells, but there was no invasion of the bronchial cartilage or visceral pleura, or any lymph node involvement. Most of the tumor cells were positive for L26 and some for UCHL-1. Although a germinal center was not seen, pseudolymphoma could not be ruled out. Southern blot analysis of the frozen tissues revealed clonal rearrangements of the immunoglobulin heavy-chain J and light-chain J, whereby the tumor was diagnosed as malignant lymphoma of the small lymphocytic B-cell type. Thus, when such lymphoproliferative diseases which are difficult to diagnose are encountered, frozen tissue should be preserved for genetic analysis. [ABSTRACT FROM AUTHOR]

The relevance of bronchus-associated lymphoid tissue (BALT) in man is still under discussion. Animal experiments indicate that the development of BALT is dependent on microbial stimulation. Therefore, the incidence of BALT was investigated retrospectively in specimens removed during surgical procedures on patients with chronic pulmonary inflammation. All these patients had severe chronic bronchitis and bronchiectasis, but BALT was found in only 8%. In patients with BALT and a malignant tumor, occlusion of a bronchus with poststenotic pneumonia was always present and BALT was observed exclusively in areas peripheral to the occlusion. In man other compartments of the lung must be responsible for the immune function of BALT found in animals. [ABSTRACT FROM AUTHOR]

The epithelium associated with lymphoid aggregates in the bronchial tract (BALT) was studied in rabbits by immunohistochemistry using monoclonal antibodies against the secretory component (SC) of IgA. The normal bronchus epithelium was intensely labelled. In contrast, epithelium overlying the central parts of the follicles was negative. This specialized epithelium cannot participate in the SC-mediated transport of IgA, which might be a basis for the adherence and transport of microorganisms into the lymphoid tissue, thus initiating immune responses of the BALT. [ABSTRACT FROM AUTHOR]