A80-4-53 A Rare Case of Pulmonary Malt Lymphoma in a 28-year- Old Man

Abstract Introduction Mucosa-associated lymphoid tissue (MALT) pulmonary lymphoma is a rare pulmonary malignancy, and its diagnosis can be difficult to establish. Case Presentation A 28-year-old male with a history of severe autism, obstructive sleep apnea on CPAP therapy, and prior COVID infection presented to outpatient clinic with an intermittent, chronic cough. Initial CT chest imaging demonstrated bilateral patchy opacities, sub-centimeter nodules and mediastinal and hilar lymphadenopathy. He underwent bronchoscopy with endobronchial ultrasound and fine needle aspiration that was negative for granulomatous disease or infection. The patient remained symptomatic with intermittent, non-productive cough that was treated with inhaled corticosteroids, bronchodilators and occasional bursts of oral prednisone. Over the next 2 years, the nodules progressed in size and number, prompting cryobiopsy of the lung and repeat endobronchial ultrasound with fine needle aspiration of hilar lymphadenopathy. Pathology demonstrated benign bronchial cells with marked acute and chronic inflammation; the biopsy was negative for granulomas or overt malignancy. Fine needle aspiration of the lymph node revealed reactive bronchial epithelial cells with lymphoid tissue. Fungal and AFB stains were negative. A video assisted right lower lobe lung biopsy was performed to establish a diagnosis. Fungal and AFB stains were negative for infection. Granulomas were absent on histological review. Flow cytometry was negative for lymphoma. However, immunochemical stains from surgical biopsy demonstrated extensive B -cell infiltrate (CD20+) extending beyond the confines of the germinal centers, distorting alveolar architecture (lymphoepithelial lesions) and lambda restriction supporting a clonal B-cell population, consistent with diagnosis of pulmonary MALT. Discussion Pulmonary MALT lymphoma is an uncommon pulmonary malignancy typically affecting patients in their 6th and 7th decade, though our patient was atypical, and manifested disease in his third decade. Our case highlights the challenges of establishing a pulmonary MALT diagnosis. Patients may exhibit mild, non-specific symptoms. CT chest findings may be varied including single or multiple pulmonary nodules, consolidations, masses, or ground glass opacities, all changes which can be suggestive of numerous disorders, including sarcoidosis or atypical bacterial or fungal infections. Only 15% of patients manifest chest adenopathy. Establishing a pulmonary MALT diagnosis may require surgical lung biopsy. While flow cytometry can be helpful in establishing the diagnosis, a negative flow cytometry does not exclude MALT. Though rare, pulmonary MALT should be considered part of the differential diagnosis for those patients with persistent pulmonary opacities in whom sarcoidosis or infectious etiologies are not evident on biopsy. This abstract is funded by: none