PNEUMONIA OR LYMPHOMA? DO NOT BE FOOLED!

Abstract

SESSION TITLE: Medical Student/Resident Lung Pathology SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: October 18-21, 2020 INTRODUCTION: Mucosa-associated lymphoid tissue (MALT) Lymphoma, also known as Extranodal Marginal Zone B cell lymphoma (EMZL), is a rare type of non-Hodgkin’s lymphoma with an incidence rate of 18.3 cases per 1 million in the United States. The objective of this case is to describe a challenging case of EMZL presenting as persistent localized lung consolidation that was mistaken for pneumonia. CASE PRESENTATION: 77-year-old male, former smoker who presented with complains of nonproductive cough for several weeks, chest-x-ray (CXR) showed a 4.3 cm rounded hazy right parahilar mass. A follow up computed tomography (CT) of the chest revealed 4.7 x2.8 cm consolidative opacity along the interlobar fissure in the right upper lobe (RUL). Reviewing back a year ago, CT scan done for nonspecific chest pain, showed the mass size was unchanged but appeared to be less solid compared to the current scan. Patient underwent a Fluorodeoxyglucose (FDG)-positron emission tomography (PET) scan which showed elevated FDG activity SUV 3.0 associated with a consolidative pulmonary opacity in the posterior portion of the right upper lobe silhouetting the major fissure. The patient subsequently underwent a CT guided percutaneous biopsy of the right upper lobe airspace consolidation. Histologic sections showed interstitial expansion and bronchial epithelium involvement by small monocytoid- appearing lymphocytes and significant amount of plasma cells (Figure 1). Immunohistochemistry was positive for CD20 and BCL-2 and negative for BCL-6 and CD10. CD138 which highlights plasma cell component was positive. Immunostaining for kappa and lambda showed findings most suggestive of monotypic lambda expression. Fluorescence in situ hybridization (FISH) studies for MALT1 (18q21) rearrangement identified a MALT1 gene rearrangement and B cell clonality studies done by PCR were positive for a clonal rearrangement. Therefore, the final diagnosis was small B-cell non-hodgkin lymphoma consistent with extranodal MALT. In retrospect the lymphoma was likely present a year ago however mistaken as a pneumonia. Given the lack of symptoms and minimal progression of over one year, was consistent with the indolent clinical behavior of the tumor. Decision was made not to treat at this point by the physician and patient. Till date patient remain asymptomatic. DISCUSSION: EMZL has been associated with persistent inflammatory state, either infectious or autoimmune in nature. EMZL can present in various ways from an incidental finding on imaging to ambiguous symptoms such as dyspnea, chest pain, cough, and rarely hemoptysis. Prognosis in MALT-type lymphomas is generally good with mean survival of more than 10 years. CONCLUSIONS: In conclusion, EMZL of the lung is uncommon and unique therefore a collaborative effort addressing early diagnosis and less invasive diagnostic testing for these high-risk EMZL patients are needed. Reference #1: Khalil MO, Morton LM, Devesa SS, et al. Incidence of marginal zone lymphoma in the United States, 2001 to 2009 with a focus on primary anatomic stie. Br J Haematol 2014; 165:67 Reference #2: Santos IG, Marchiori E, Zanetti G, Mano CM, SarcielliLuz B, Vianna FG. Primary pulmonary mucosaasociated lymphoid tissue lymphoma computed tomography findings: A case report. Cases J. 2009;2:6329. [PMCID:PMC2740136] [PubMed: 19829788] DISCLOSURES: No relevant relationships by Hussein Hussein, source=Web Response No relevant relationships by Ahmad JABRI, source=Web Response No relevant relationships by Sonya Joshi, source=Web Response No relevant relationships by Sujith Modugula, source=Web Response No relevant relationships by Elizabeth Verghese, source=Web Response