High-resolution computed tomographic appearance of MALToma of the lung

MALToma of the lung is rare and advances in molecular techniques have only recently allowed accurate diagnostic classification of the previously termed "pseudolymphomas" by demonstrating that many are monoclonal B-cell proliferations of MALT tissue and therefore true low-grade lymphomas. No significant previous contribution was found in the literature regarding the high-resolution CT appearance (HRCT) of these tumours. We describe the high-resolution CT appearances in five cases presenting to our institution from 1994 to 1997. The HRCT scans (1-mm sections at 10- to 15-mm intervals) were performed as the opacities seen radiographically were thought to be part of a diffuse lung process. In one patient a spiral sequence was performed through the main airway. Multifocal, ill-defined nodules containing air bronchograms were seen in four cases and focal lobar consolidation in one case. Interlobular septal thickening, centrilobular micronodules and bronchial wall thickening were seen in two cases. Mediastinal lymphadenopathy and pleural reaction do not appear to be characteristic features. The appearance of multifocal consolidation is similar to that seen in bronchoalveolar cell carcinoma and cryptogenic organising pneumonia.