Mucosa-associated lymphoid tissue (MALT) lymphoma is an indolent non-Hodgkin B-cell lymphoma most often found in the gastric mucosa. The lymphoma cells infiltrate around reactive secondary follicles in a marginal zone distribution; hence, they are also labeled marginal zone lymphoma (MZL). When arising from lymphoid cells in the submucosal area of bronchioles, it is referred to as bronchus-associated lymphoid tissue (BALT) lymphoma. BALT is a diagnostic challenge, usually requiring either a thoracotomy or a video-assisted thoracoscopy for lung biopsy. The case herein describes a man with a remote history of gastric MALT lymphoma presenting with a lung mass, who on bronchoscopic evaluation was found to have a recurrence of MZL.
A 65-year-old man with a history of hepatitis C, treated latent tuberculosis (TB), and gastric MALT lymphoma 10 years earlier status post chemotherapy was evaluated for a 7×5 cm right lower lobe mass on computed tomography. He reported a cough productive of yellowish sputum but was otherwise asymptomatic. His physical examination was unremarkable.
Bronchoscopy revealed abnormal mucosa in the posterior basal segment of the right lower lobe (Fig. 1). Bronchoalveolar lavage, transbronchial needle aspiration, and endobronchial biopsies were performed at this site. The biopsies and needle aspirate yielded similar results, small lymphoid cells within a background of chronic inflammation. Immunostainings revealed a large population of B lymphocytes (Fig. 2) with limited T lymphocytes. Flow cytometric analysis of the needle aspirate was indicative of a monoclonal process consistent with MZL. Histopathology from the lung lesion was compared with a gastric antrum biopsy from his prior MALT and was found to be consistent. A diagnosis of pulmonary recurrence of gastric MALT lymphoma was made.
MALT lymphoma is a low-grade B-cell MZL and is subdivided on the basis of the involvement of node, extranodal tissue (MALT), or spleen. MALT lymphomas arise from lymphoid aggregates such as Peyer's patches or de novo from sites of chronic inflammation, often secondary to infection or autoimmune disease. The majority arises in the gastrointestinal mucosa, although they can arise in other locations including the lung,1 where it is often referred to as BALT lymphoma. Although chronic inflammation associated with Helicobacter pylori is the most frequent impetus for clonal proliferation in the gastric mucosa, BALT lymphoma has yet to be associated with any specific organism.2 It has been reported that the risk of non-Hodgkin lymphoma may increase in patients with a distant history of severe TB.3 However, the patient presented herein had only a prior positive purified protein derivative skin test and was treated for latent TB. Hepatitis C infection is also associated with various low-grade B-cell lymphomas,4 but it is unclear whether a relationship between hepatitis C and BALT lymphoma exists.
The diagnosis of MALT lymphoma of the lung can be difficult. Radiographic findings, most commonly, consolidation with air bronchograms,5 are nonspecific. In the past, evaluation of the tissue architecture through transbronchial or surgical lung biopsies has been necessary for BALT lymphoma diagnosis. However, in our patient, the bronchoscopic samples collected by transbronchial needle aspiration for cytology and flow cytometry helped clinch the diagnosis, highlighting the benefits of this diagnostic modality. The potential of transbronchoscopic needle aspiration for diagnosis of lymphoma, specifically BALT, has been alluded to in very limited pathologic studies.6 This case strengthens the contention that it should be part of the procedure in all bronchoscopies performed on individuals suspected to have these disease processes.
MZL of the lung is a diagnostic challenge for which no one approach is best. Bronchoscopy with transbronchial needle aspiration sent for flow cytometry should be considered as a diagnostic modality in these patients, as it has significantly less morbidity compared with surgical options.
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