Extensive Cystic Lung Disease in Extranodal Marginal Zone B Cell Lymphoma (Malt Lymphoma) of the Lung With Light Chain Deposition Disease

Abstract

INTRODUCTION:Extranodal marginal zone lymphoma of mucosa associated lymphoid tissue (MALT Lymphoma) is a rare disorder, but is the most common cause of primary pulmonary lymphoma involvement. Cystic changes along with nodularity has been previously reported in MALT lymphomas along with light chain deposition disease (LCDD). CASE PRESENTATION:A 44 y/o previously smoking female patient presented with a 3-year history of progressive dyspnea in the setting of extensive cystic lung disease. Her extensive lung cysts had previously raised concern for lymphangioleiomyomatosis (LAM) and she had undergone an open lung biopsy (OLB) about 2 years prior. She also had a 10-year history of Rheumatoid Arthritis (RA) for which she had previously received methotrexate, adalimumab and leflunomide. The OLB was negative for LAM, but no alternative diagnosis was made based on the biopsy results. Due to progressive dyspnea, she presented to our facility where a fresh evaluation of her case was undertaken. A repeat CT Chest again confirmed extensive cystic lung changes that were not present 12 years ago and had minimally progressed from the time of OLB two years ago (figure 1). Pulmonary function testing (PFTs) showed a severe obstructive pattern with a positive bronchodilator response. Laboratory testing confirmed positive results for rheumatoid factor, CCP, ANA as well as SSA & SSB antibodies. A review of the OLB confirmed the presence of an atypical lymphoplasmacytic infiltrate associated with nodular kappa light chain deposition disease (LCDD). The overall pattern was consistent with extranodal marginal zone lymphoma of mucosa associated lymphoid tissue (MALT lymphoma). The biopsy confirmed the presence of cystic changes within the nodular light chain deposits. PET scan was negative for extrathoracic lymphoma and the patient was started on Rituximab.DISCUSSION: We present a case of pulmonary MALT Lymphoma with LCDD presenting with extensive cystic lung disease and severe airflow obstruction. The case was initially mistaken for LAM and appropriate therapy was delayed for 2 years. MALT lymphomas with LCDD are rare causes of pulmonary cystic disease and generally have a good prognosis with an overall 5-year survival rate exceeding 80% and a median survival over 10 years. Given the positive Sjogren's antibodies and the presence of lung cysts; lymphocytic interstitial pneumonia (LIP) was also considered in the differential diagnosis. The presence of severe airflow obstruction on lung function was somewhat atypical in this case and a component of bronchiolitis obliterans from RA could not be entirely excluded. CONCLUSIONS:Extranodal marginal zone B cell lymphoma of the lung can present with extensive cystic lung disease that can mimic other common causes of cystic lung disease such as LAM, LIP and Birt Hogg Dube disease and PLCH. Prognosis is generally good and Rituximab is the most commonly used initial treatment approach.