Malignant and benign lymphoid lesions of the lung

Marginal zone lymphoma of extranodal sites: A review with an emphasis on diagnostic pitfalls and differential diagnosis with reactive conditions

Marginal zone lymphoma of the mucosa-associated lymphoid tissue (MALT lymphoma) represents 8% of all B-cell lymphomas and it is the most common small B-cell lymphoma arising at extranodal sites. The gold-standard test to establish a diagnosis of MALT lymphoma remains histopathologic analysis with the aid of immunohistochemistry (IHC) and/or flow cytometry immunophenotypic analysis. MALT lymphoma represents a progression from a persistent chronic inflammatory process, and therefore distinguishing MALT lymphoma from chronic inflammation by histopathology may be challenging in some cases. Despite recent trends to consider IGH rearrangement/clonality as a confirmatory diagnostic test of MALT lymphoma, this method is far from ideal for this purpose since a positive or a negative result does not necessarily confirm or exclude that a process is lymphoma or reactive. This test must be correlated with the morphologic findings. Moreover, MALT lymphoma may arise in association with underlying autoimmune conditions where clonal lymphoid populations are not uncommonly detected. Therefore, we believe that an integrated approach including detailed morphologic review in combination with IHC and/or flow cytometry is best to establish a diagnosis of MALT lymphoma in most cases. We present helpful morphologic tips to avoid potential diagnostic pitfalls at some of the most common extranodal sites, including the stomach, ocular adnexa/conjunctiva, salivary gland, lung, thymus, breast, thyroid, small and large intestine and the dura. The differential diagnosis of MALT lymphoma with IgG4-related disease is also discussed.

Anaemia of Inflammation Preceding Dyspnoea, Dry Cough and Weight Loss in Primary Pulmonary Lymphoma

Introduction

There is little information in the literature on the early, sub-clinical stage and laboratory test results in patients with primary mucosa-associated lymphoid tissue (MALT) lymphoma of the lung, a rare disease.

Case description

In a 75-year-old man, an open lung biopsy-confirmed diagnosis of primary pulmonary lymphoma was preceded by almost six months of anaemia of inflammatory disease and monocytosis without any pulmonary symptoms. When he developed a dry cough, increasing dyspnoea and marked weight loss, these changes deepened and became associated with reactive thrombocytosis; markedly increased ferritin and C-reactive protein (positive acute-phase reactants), as well as reduced albumin and transferrin (negative acute-phase reactants). Globulins increased, due to an increase in the alpha1, alpha2 and gamma fractions, and mild hyponatraemia developed due to the syndrome of inappropriate antidiuretic hormone secretion (SIADH) secondary to the intrathoracic disease. All these changes were completely reversible following successful treatment and complete remission.

Conclusion

The previously unreported detailed laboratory features of early, sub-clinical and advanced primary pulmonary lymphoma are presented. When a potentially susceptible patient develops an unexplained anaemia of inflammatory disease, primary pulmonary lymphoma should be added to the differential diagnosis.

LEARNING POINTS

B-cell pulmonary lymphoma without extra-pulmonary disease (primary pulmonary lymphoma) remains a rare entity, often arising from mucosa-associated lymphoid tissue, presenting with non-specific symptoms (cough, dyspnoea) and imaging (nodules <5 cm or areas of consolidation on CT), and diagnosed by an adequate biopsy.Our patient's course demonstrates early, pre-clinical changes: anaemia of inflammation and monocytosis, which became more severe as symptoms developed and imaging abnormalities progressed, and was associated with marked acute-phase response (for example, substantially increased ferritin levels), increased globulins and hyponatraemia due to the syndrome of inappropriate antidiuretic hormone secretion.In patients with unexplained anaemia of inflammatory disease, occult pulmonary lymphoma should be considered in the differential diagnosis.

Harnessing the potential of the NALT and BALT as targets for immunomodulation using engineering strategies to enhance mucosal uptake

Mucosal barrier tissues and their mucosal associated lymphoid tissues (MALT) are attractive targets for vaccines and immunotherapies due to their roles in both priming and regulating adaptive immune responses. The upper and lower respiratory mucosae, in particular, possess unique properties: a vast surface area responsible for frontline protection against inhaled pathogens but also simultaneous tight regulation of homeostasis against a continuous backdrop of non-pathogenic antigen exposure. Within the upper and lower respiratory tract, the nasal and bronchial associated lymphoid tissues (NALT and BALT, respectively) are key sites where antigen-specific immune responses are orchestrated against inhaled antigens, serving as critical training grounds for adaptive immunity. Many infectious diseases are transmitted via respiratory mucosal sites, highlighting the need for vaccines that can activate resident frontline immune protection in these tissues to block infection. While traditional parenteral vaccines that are injected tend to elicit weak immunity in mucosal tissues, mucosal vaccines (i.e., that are administered intranasally) are capable of eliciting both systemic and mucosal immunity in tandem by initiating immune responses in the MALT. In contrast, administering antigen to mucosal tissues in the absence of adjuvant or costimulatory signals can instead induce antigen-specific tolerance by exploiting regulatory mechanisms inherent to MALT, holding potential for mucosal immunotherapies to treat autoimmunity. Yet despite being well motivated by mucosal biology, development of both mucosal subunit vaccines and immunotherapies has historically been plagued by poor drug delivery across mucosal barriers, resulting in weak efficacy, short-lived responses, and to-date a lack of clinical translation. Development of engineering strategies that can overcome barriers to mucosal delivery are thus critical for translation of mucosal subunit vaccines and immunotherapies. This review covers engineering strategies to enhance mucosal uptake via active targeting and passive transport mechanisms, with a parallel focus on mechanisms of immune activation and regulation in the respiratory mucosa. By combining engineering strategies for enhanced mucosal delivery with a better understanding of immune mechanisms in the NALT and BALT, we hope to illustrate the potential of these mucosal sites as targets for immunomodulation.

Diagnostic Approach to Pulmonary B-Cell Lymphomas in Small Biopsies, with Practical Recommendations to Avoid Misinterpretation

Pulmonary lymphomas are rare. With the current less invasive approaches used to obtain material for diagnosis, the diagnosis of pulmonary lymphoma is now frequently established in a small biopsy rather than in a resection. Therefore, the diagnosis has become more challenging and requires correlation with the clinico-radiologic presentation and with ancillary studies (immunohistochemistry, flow cytometry, cytogenetics, and/or molecular analysis). Due to the rarity of pulmonary lymphomas, clinical suspicion of a lymphomatous process is low at initial presentation, and material may be only submitted for histopathology. For this reason, herein, we provide recommendations to arrive at the correct diagnosis of the most common lung B-cell lymphomas (marginal zone lymphoma of mucosa-associated lymphoid tissue, diffuse large B-cell lymphoma, intravascular large B-cell lymphoma, lymphomatoid granulomatosis) in the setting of small biopsies, utilizing only immunohistochemistry. The differential diagnosis varies according to the lymphoma subtype and includes reactive conditions, solid tumors, and other hematolymphoid malignancies. Although morphology and immunohistochemistry may be sufficient to establish a diagnosis, in some cases, the best recommendation is to obtain additional tissue via a VATS biopsy/wedge resection with material submitted for flow cytometry, cytogenetics, and/or molecular studies to be able to properly classify a pulmonary lymphoid process.

Primary Lymphoproliferative Lung Diseases: Imaging and Multidisciplinary Approach

Lymphoproliferative lung diseases are a heterogeneous group of disorders characterized by primary or secondary involvement of the lung. Primary pulmonary lymphomas are the most common type, representing 0.5–1% of all primary malignancies of the lung. The radiological presentation is often heterogeneous and non-specific: consolidations, masses, and nodules are the most common findings, followed by ground-glass opacities and interstitial involvement, more common in secondary lung lymphomas. These findings usually show a prevalent perilymphatic spread along bronchovascular bundles, without a prevalence in the upper or lower lung lobes. An ancillary sign, such as a “halo sign”, “reverse halo sign”, air bronchogram, or CT angiogram sign, may be present and can help rule out a differential diagnosis. Since a wide spectrum of pulmonary parenchymal diseases may mimic lymphoma, a correct clinical evaluation and a multidisciplinary approach are mandatory. In this sense, despite High-Resolution Computer Tomography (HRCT) representing the gold standard, a tissue sample is needed for a certain and definitive diagnosis. Cryobiopsy is a relatively new technique that permits the obtaining of a larger amount of tissue without significant artifacts, and is less invasive and more precise than surgical biopsy.

Nodular Lymphoid Hyperplasia as Incidental Finding of Suspect Pulmonary Mass

Nodular lymphoid hyperplasia of the lung is a rare disease of polyclonal lymphoid proliferation. The incidental finding of a solid nodular lesion with irregular margins adjacent to the visceral pleura in the reported case was highly suggestive of malignancy. The present report underscores the typical immunohistochemical findings and the benign course of nodular lymphoid hyperplasia. The current knowledge about disease aetiology and the value of different diagnostic tools to distinguish nodular lymphoid hyperplasia from other pulmonary lymphoid lesions are summarized by a review of the literature. Surgical resection is not only diagnostic but also curative with no evidence so far that NLH can regress without operation. The present case shows the spontaneous regression of NLH after CT-guided biopsy indicating that an alternative, less invasive diagnostic approach has curative potential.

Primary Pulmonary B-Cell Lymphoma: A Review and Update

Simple Summary

The group of B-cell lymphomas primarily involving the lung encompasses different histological entities with distinct biological aspects, while sharing some clinical and radiological features related to their common anatomic site of occurrence. Recent molecular advances in the molecular genetics of these lesions have substantially improved of our understanding of the mechanisms of lymphomagenesis, adding novel information to histology in order to better characterize and manage these diseases. This review summarizes the available clinical, radiological, pathological, and molecular data on primary pulmonary B-cell lymphomas, discusses the mechanisms of lymphomagenesis, and highlights the role of a multi-disciplinary management in overcoming the diagnostic and therapeutic challenges in this setting.

Abstract

Primary pulmonary B-cell lymphomas (PP-BCLs) comprise a group of extranodal non-Hodgkin lymphomas of B-cell origin, which primarily affect the lung without evidence of extrapulmonary disease at the time of diagnosis and up to 3 months afterwards. Primary lymphoid proliferations of the lung are most often of B-cell lineage, and include three major entities with different clinical, morphological, and molecular features: primary pulmonary marginal zone lymphoma of mucosa-associated lymphoid tissue (PP-MZL, or MALT lymphoma), primary pulmonary diffuse large B cell lymphoma (PP-DLBCL), and lymphomatoid granulomatosis (LYG). Less common entities include primary effusion B-cell lymphoma (PEL) and intravascular large B cell lymphoma (IVLBCL). A proper workup requires a multidisciplinary approach, including radiologists, pneumologists, thoracic surgeons, pathologists, hemato-oncologists, and radiation oncologists, in order to achieve a correct diagnosis and risk assessment. Aim of this review is to analyze and outline the clinical and pathological features of the most frequent PP-BCLs, and to critically analyze the major issues in their diagnosis and management.

Pulmonary nodular lymphoid hyperplasia in pediatric patients with Hodgkin lymphoma

Pulmonary lymphoid lesions span from benign to other forms of malignant diseases. Among these pulmonary lymphoid lesions, Nodular Lymphoid Hyperplasia (NLH) has an excellent prognosis. The surgical excision of NLH seems to be the only treatment, even if in some cases a spontaneous regression has been reported. Interestingly, these lesions may have similar clinical and radiographic presentations, making a histopathological examination vital for their differentiation. In this report we describe four cases of pediatric patients with a previous history of classical Hodgkin Lymphoma (HL) with documented or suspected NLH.

Primary pulmonary lymphoma: imaging findings in 30 cases

PURPOSE

To present our experience of cases of primary pulmonary lymphoma (PPL) found between January 2002 and July 2018, focusing on the radiological features and the differential diagnosis in order to contribute to the difficult role of the radiologist in the disease identification and to help the clinicians to reach the diagnosis.

MATERIALS AND METHODS

CT scans of 30 patients (14 men and 16 women, aged 58-86, mean age 72 years) with PPL were retrospectively reviewed. All patients had a histopathological confirmation of the disease: MALT lymphoma (23 patients, 76.6%); diffuse large B-cell lymphoma-DLBCL (seven patients, 23.4%). All the staging CT scans were evaluated by three experienced radiologists dedicated to thoracic disease in order to radiologically define the predominant pattern of presentation.

RESULTS

The following parenchymal patterns were observed: 11 patients with single/multiple nodules, five with masses/mass-like consolidations, 14 with consolidations with air bronchogram, 16 with ground-glass opacity, ten with angiogram sign, 22 with perilymphatic and/or peribronchovascular spread, 15 with associated lymphadenopathies, and 13 with pleural/chest wall involvement. The main characteristics of PPLs were the presence of consolidations and ground-glass opacities, with perilymphatic and/or bronchovascular spread.

CONCLUSION

All the characteristics of the work should alert the radiologist to consider lymphoma among the possible differential diagnoses, always correlating the results of the CT examination with appropriate clinical laboratory evaluations.

Pulmonary MALT Lymphoma has variable features on CT

Pulmonary mucosa-associated lymphoid tissue (MALT) lymphoma is the most common primary pulmonary lymphoma. There are limited studies on imaging features of pulmonary MALT lymphoma. We present the computed tomography (CT) manifestations of pulmonary MALT lymphoma and the correlation between CT manifestations and clinical characteristics. Patients (n = 53) with histologically confirmed pulmonary MALT lymphoma who underwent chest CT scanning were retrospectively analyzed. Evaluated findings included distribution of pulmonary lesions, morphological pattern of appearance, contrast enhancement features, size, presence of thoracic lymphadenopathy, and secondary associated features. Pulmonary MALT lymphoma was observed in multiple (79%) and bilateral (66%) disease with random distribution (≥70%) of pulmonary lesions. The most frequent morphological pattern was consolidation (n = 33, 62%), followed by nodule (n = 23, 43%) and mass (n = 11, 21%). Common associated features were air bronchograms and bronchiectasis, especially cystic bronchiectasis and angiogram sign. Asymptomatic patients had less consolidation and bronchiectasis than did symptomatic patients. Cystic bronchiectasis was only observed in the symptomatic group. In conclusion, pulmonary MALT lymphoma manifests as diverse patterns on CT scans. Consolidation combined with cystic bronchiectasis was a characteristic late sign, which may assist in differential diagnosis. High-resolution CT images and multiplanar reconstruction techniques are helpful for accurately determining imaging manifestations.

Clinical features and outcomes of pulmonary lymphoma: A single center experience of 180 cases

BACKGROUND

Pulmonary lymphoma arises primarily from the lung, which is extremely rare, or be secondarily involved by lymphoma. The clinical features, management, and prognostic factors have not been clearly identified.

METHODS

Sixty-three patients with primary pulmonary lymphoma (PPL) and 117 patients with secondary pulmonary lymphoma (SPL) treated in our institution between June 2003 and December 2017 were retrospectively reviewed.

RESULTS

MALT (67%) was the most common pathological subtype of PPL, while DLBCL (48%) was the most common subtype of SPL. Compared to the patients with PPL, the presence of B symptoms, advanced disease stage, intermediate-high or high risks of IPI and NCCN-IPI, elevated inflammatory parameters, and elevated cytokine levels were all observed in patients with SPL. Consolidation was the most frequent radiological finding in PPL cases, while nodules were the most frequent finding in SPL. With a median follow-up of 35 months (range 2-176), the estimated 3-year OS rates were 95%, 100%, 70% and 50% in indolent PPL, indolent SPL, aggressive PPL, and aggressive SPL, respectively. In indolent pulmonary lymphoma, none of the prognostic factors we studied significantly influenced survival of the patients. In aggressive pulmonary lymphoma, univariate analysis showed that NCCN-IPI was related to OS in PPL. Multivariate analysis showed that β2-MG was an independent prognostic factor for OS in SPL.

CONCLUSIONS

Primary and secondary pulmonary lymphoma differ in their clinical features and outcome. Furthermore, β2-MG is the independent prognostic factor for OS in patients with aggressive SPL.

A 48-Year-Old Man With Multiple Pulmonary Nodular Opacities and Elevated KL-6 Level

A 48-year-old man was referred for evaluation of an abnormal chest shadow noted on a routine chest radiograph during physical examination. He was asymptomatic and had no significant medical history and occupational exposure. The patient lived in Tokyo and had no significant travel history. He had smoked approximately 20 cigarettes daily for 20 years. He had no illicit drug use and no animal-rearing history.

Primary Pulmonary Extranodal Marginal Zone Lymphoma/Low Grade B-cell Lymphoma of MALT Type Combined with Well-Differentiated Adenocarcinoma

We describe a rare case of extranodal marginal zone/low-grade B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) combined with areas of well-differentiated adenocarcinoma. In addition, the MALT lymphoma was synchronously systemic, with involvement of the lung, stomach and duodenum.

Multiple Mucosa-associated Lymphoid Tissue Lymphoma of the Trachea

Mucosa-associated lymphoid tissue lymphoma is a common type of primary pulmonary carcinoma, but the presence of polypoid nodules is extremely rare. We herein report two cases with multiple nodules in the trachea. One case involved polypoid nodules and airway stenosis mimicking asthma; the other case had concurrent nontuberculous mycobacterial infection. The diagnosis of both cases was confirmed by bronchoscopy. The two cases were sensitive to radiotherapy and chemotherapy, respectively.

Primary Pulmonary Lymphoid Lesions: Radiologic and Pathologic Findings

The pulmonary lymphoid system is complex and is composed of two compartments: the pulmonary lymphatics and the bronchus-associated lymphoid tissue (BALT). Additional important cells that function in the pulmonary lymphoid system include dendritic cells, Langherhans cells, macrophages, and plasma cells. An appreciation of the normal lymphoid anatomy of the lung as well as its immunology is helpful in understanding the radiologic and pathologic findings of the primary pulmonary lymphoid lesions. Primary lymphoid lesions of the lung arise from the BALT and are uncommon. However, they are increasingly recognized within the growing number of posttransplant patients as well as other patients who are receiving immunosuppressive therapies. Primary lymphoid lesions encompass a wide range of benign and malignant lesions. Benign lymphoid lesions of the lung include reactive lymphoid hyperplasia, follicular bronchiolitis, lymphoid interstitial pneumonia, and nodular lymphoid hyperplasia. Malignant lymphoid lesions of the lung include low-grade B-cell lymphoma of mucosa-associated lymphoid tissue (MALT), other non-Hodgkin lymphomas, and Hodgkin lymphoma. Last, a miscellaneous group of primary lymphoid lesions includes lymphomatoid granulomatosis, posttransplant lymphoproliferative disorders, acquired immunodeficiency syndrome (AIDS)-related lymphoma, and intravascular lymphoma/lymphomatosis. These lesions are best evaluated with multidetector chest computed tomography. The radiologic findings of the primary lymphoid lesions are often nonspecific and are best interpreted in correlation with clinical data and pathologic findings. The purpose of this article is to review pulmonary lymphoid anatomy as well as the most common primary pulmonary lymphoid disorders.

Primary Pulmonary Lymphomas

Primary lung lymphoma (PLL) is a rare disease that comprises <0.5% of all primary lung tumors. It is defined as lymphoma confined to the lung with or without hilar lymph node involvement at the time of diagnosis or up to 3 months thereafter. Patients with PLL may be asymptomatic or manifest nonspecific clinical symptoms, for example, cough, chest pain, and dyspnea. Some individuals may be immunosupressed or have an autoimmune disorder. Radiologically, PLL can mimic pneumonia, lung carcinoma, or metastasis, and therefore, histologic confirmation is mandatory for definitive diagnosis. Primary lung marginal zone lymphoma of mucosa-associated lymphoid tissue type comprises 70% to 80% of cases. Less common B-cell lymphomas include diffuse large B-cell lymphoma, lymphomatoid granulomatosis (LyG), plasmacytoma, and other small lymphocytic lymphomas. PLLs of T-cell origin, largely represented by anaplastic large cell lymphoma, are extremely rare. LyG is an Epstein-Barr virus (EBV)-driven B-cell lymphoid neoplastic proliferation rich in T cells that produces vasculitis. The disease may present at different stages of progression. Differential diagnosis of PLL varies according to the lymphoma subtype: pulmonary mucosa-associated lymphoid tissue lymphoma should be distinguished from reactive inflammatory conditions, whereas high-grade lymphomas may resemble poorly differentiated lung carcinoma, metastatic disease, and other lymphomas. LyG can resemble inflammatory, infectious, and other lymphoid neoplastic processes. A panel of immunohistochemical markers, flow cytometry, and molecular methods are necessary to confirm the diagnosis in the majority of cases. In this article we review the clinical, radiologic, pathologic, and molecular characteristics of several B-cell and T-cell PLLs with exception of Hodgkin lymphoma and posttransplant lymphoproliferative disorder.

Marginal zone B-cell lymphoma of the pulmonary mucosa-associated lymphoid tissue: A case report

Marginal zone B-cell lymphoma of the pulmonary mucosa-associated lymphoid tissue (pulmonary MALT-MZL) is a common type of primary pulmonary lymphoma, but is rare as a pulmonary malignant tumor. In the present study, a 49-year-old male patient was admitted to The First Affiliated Hospital of Xi'an JiaTong University (Xi'an, China) with a pulmonary lesion in the right upper lung. The patient was diagnosed with pulmonary MALT-MZL subsequent to undergoing chest computed tomography (CT), a routine blood test, pathological and histological examinations, a transbronchial lung biopsy and bronchoscopy. A chest CT scan revealed right middle lobe consolidation and inflammatory signs, accompanied by mediastinal lymphadenopathy in the anterior basal segment of the upper lobe and CT angiogram signs. Bronchial stenosis and swollen mucosa were observed by bronchoscopy. The tissue section of the transbronchial lung biopsy specimens revealed diffusely infiltrated monocytoid B-cell lymphocytes and a lymphoepithelial lesion. The tissue was found to be positive for cluster of differentiation (CD)20, B-cell lymphoma 2 and CD79a expression, but negative for CD3, CD5, cyclin D1 and κ-light chain expression. CD21 and CD23, located in the residual follicular dendritic cells, were detected by immunohistochemical staining. The clinical manifestations of pulmonary MALT-MZL are non-specific and misdiagnosis frequently occurs in clinical practice. Therefore, an appropriate invasive biopsy procedure is necessary for early and accurate diagnosis of pulmonary MALT-MZL. Clinical presentation that includes periodic fever and distended bronchi in pulmonary consolidation may indicate a diagnosis of MALT-MZL. Pulmonary MALT-MZL belongs to the category of indolent lymphoma and accurate clinical diagnosis is challenging. The results in the present study may provide additional evidence for the accurate diagnosis of this rare entity.

Extranodal Marginal Zone Lymphoma of the Lung: Evolution from an Underlying Reactive Lymphoproliferative Disorder

Extranodal Marginal Zone Lymphoma (ENMZL) of Mucosa-Associated Lymphoid Tissue (MALT) is a problematic and sometimes controversial diagnosis. While commonly seen in the stomach in the setting of chronic Helicobacter pylori infection, other extranodal sites, such as the lung, may also present with disease. ENMZL is clinically and morphologically heterogeneous; however, regardless of presentation, the etiology lies in the accumulation of lymphoid tissue in non-traditional sites. This phenomenon is typically secondary to an underlying inflammatory stimulus such as chronic infection or autoimmune states. The current case report details the clinical history of a patient with Sjögren syndrome over a four year period who eventually developed ENMZL. The patient initially presented with an atypical, but polyclonal, lymphoproliferative process diagnosed as lymphocytic interstitial pneumonia. Over time, the patient showed evolution to a monoclonal process with associated radiologic progression of disease. This evolution manifested as a dense lymphoid infiltrate with prominent plasmacytic differentiation and the development of a lung mass radiologically. This case contributes to the growing body of knowledge that suggests ENMZL lies along a biological spectrum of lymphoproliferative disorders whereby a benign, reactive process may eventually undergo malignant transformation. This evolution likely represents the acquisition of genetic abnormalities that allow autonomous proliferation in the absence of the initial immune stimulus. In practice, determining when this event occurs and, thus, distinguishing between reactive and neoplastic disorders within this spectrum may be difficult as no single clinicopathologic feature may be present to establish the diagnosis. This case further illustrates the importance of correlating the clinical, radiologic and pathologic data to evaluate patients with atypical pulmonary lymphoproliferative disorders and to allow the optimal management of their disease.

Structure, Organization, and Development of the Mucosal Immune System of the Respiratory Tract

The respiratory tract is served by a variety of lymphoid tissues, including the tonsils, adenoids, nasal-associated lymphoid tissue (NALT), and bronchus-associated lymphoid tissue (BALT), as well as the lymph nodes that drain the upper and lower respiratory tract. Each of these tissues uses unique mechanisms to acquire antigens and respond to pathogens in the local environment and supports immune responses that are tailored to protect those locations. This chapter will review the important features of NALT and BALT and define how these tissues contribute to immunity in the upper and lower respiratory tract, respectively.

An Unusual Presentation of Pulmonary Mucosa-Associated Lymphoid Tissue Lymphoma as Diffuse Pulmonary Infiltrates with Spontaneous Regression

A 57-year-old woman presented with cough and dyspnea for 2 months. Computed tomography of the chest showed diffuse ground-glass opacities in both lungs. Histologic examination via thoracoscopic lung biopsy revealed atypical lymphoproliferative lesion. Her symptoms and radiologic findings of the chest improved just after lung biopsy without any treatment. Therefore, she was discharged and monitored at an outpatient clinic. Two months later, pulmonary mucosa-associated lymphoid tissue (MALT) lymphoma was confirmed by the detection of API2-MALT1 translocation in fluorescent in situ hybridization analysis. Although the lung lesions resolved spontaneously, she received chemotherapy due to bone marrow involvement in her staging workup. Pulmonary MALT lymphoma is rare. Nodular or consolidative patterns are the most frequent radiologic findings. Although the disease has an indolent growth, it rarely resolves without treatment. We report an unusual case of pulmonary MALT lymphoma with diffuse interstitial abnormalities on image and spontaneous regression on clinical course.

Lymphoproliferative lung disorders: a radiologic-pathologic overview. Part I: Reactive disorders

Lymphoid tissue is a normal component of the lung and manifests as intrapulmonary lymph nodes, bronchus-associated lymphoid tissue (BALT), peripheral lymphocytic aggregates, solitary lymphocytes, and phagocytic cells. Pulmonary lymphoid lesions are thought to develop as a consequence of anomalous stimulation and response of the bronchus-associated lymphoid tissue and manifests as a spectrum of lymphoproliferative disorders that may be reactive or neoplastic. Reactive disorders are polyclonal abnormalities and include nodular lymphoid hyperplasia, lymphocytic interstitial pneumonia, follicular bronchiolitis, angiofollicular hyperplasia, and enlarged intrapulmonary lymph nodes. Affected patients are often asymptomatic. Imaging findings include focal nodules, diffuse bilateral centrilobular nodules, and hilar or mediastinal masses.

A Case of Synchronous Lung Adenocarcinoma and Extranodal Marginal Zone B-Cell Lymphoma of Mucosa-Associated Lymphoid Tissue (MALT) Type

Extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue type (extranodal MZL) is a distinct subgroup of non-Hodgkin's lymphoma. Pulmonary extranodal MZL is a rare entity and accounts for less than 0.5% of primary pulmonary malignancies. Only a few cases of simultaneous occurrence of lung cancer and pulmonary extranodal MZL have been reported. A 60-year-old woman was referred to our hospital with a pulmonary nodule. She was diagnosed with lung adenocarcinoma by percutaneous needle biopsy. The protrusions into the left main bronchus were found by accident while performing bronchoscopy during lung cancer evaluation. The bronchial lesions were diagnosed as extranodal MZL. Although the patient underwent surgical resection for the lung adenocarcinoma, the pulmonary extranodal MZL was left untreated; it was monitored during follow-up visits. To our knowledge, this is the first report of synchronous lung adenocarcinoma and primary extranodal MZL of the main bronchus.

Bronchus-associated lymphoid tissue (BALT) structure and function

Bronchus-associated lymphoid tissue (BALT) is a constitutive mucosal lymphoid tissue adjacent to major airways in some mammalian species, including rats and rabbits, but not humans or mice. A related tissue, inducible BALT (iBALT), is an ectopic lymphoid tissue that is formed upon inflammation or infection in both mice and humans and can be found throughout the lung. Both BALT and iBALT acquire antigens from the airways and initiate local immune responses and maintain memory cells in the lungs. Here, we discuss the development and function of BALT and iBALT in the context of pulmonary immunity to infectious agents, tumors, and allergens as well as autoimmunity and inflammatory diseases of the lung.

Padrões tomográficos das doenças intersticiais pulmonares difusas com correlação clínica e patológica

A tomografia de alta resolução (TCAR) é a técnica de imagem radiológica que reflete mais de perto as alterações da estrutura pulmonar. Os vários achados tomográficos podem ser combinados para formar padrões típicos. Estes, conjuntamente com a distribuição anatômica dos achados, e com os dados clínicos, podem estreitar o diagnóstico das doenças intersticiais pulmonares difusas, e em vários casos sugerir o diagnóstico correto com alto grau de acurácia. Os padrões mais comuns das doenças intersticiais pulmonares difusas na TCAR são o nodular, linear e reticular, lesões císticas, opacidades em vidro fosco e consolidações. Este artigo revisa as correlações entre os padrões tomográficos na TCAR e os achados patológicos e resume as causas mais comuns e os métodos de investigação para se atingir um diagnóstico nas doenças pulmonares crônicas difusas mais comuns.

Avoiding underdiagnosis, overdiagnosis, and misdiagnosis of lung carcinoma

CONTEXT

Given the magnitude of the therapeutic and prognostic implications, it is critical that pathologists diagnose lung cancer accurately. This can sometimes be a formidable challenge, as a number of benign entities mimic lung carcinoma and vice versa.

OBJECTIVE

To present strategies for recognizing benign entities likely to be confused with lung carcinoma, malignancies of the lung prone to misinterpretation as benign, and commonly misclassified pulmonary neoplasms.

DATA SOURCES

The medical literature and experience from consultative and surgical practice.

CONCLUSIONS

In addition to understanding the clinical context in which a lung biopsy is procured and the radiographic findings, appreciating the histologic distribution of disease and what, if any, pathologic features are present in the background can go a long way toward averting a misdiagnosis of lung cancer. Recognizing the limitations posed by small samples and communicating clearly to clinicians the level of diagnostic uncertainty are equally as important for establishing an accurate diagnosis of lung cancer.

Hodgkin lymphoma presenting with exclusive or preponderant pulmonary involvement: a clinicopathologic study of 5 new cases

A review of the pathological features of Hodgkin lymphoma manifesting with exclusive or preponderant lung involvement is given for 5 patients. Three patients were men and 2 were women, with an age range 17 to 48 years (median, 42 years). They presented with nonspecific symptoms including dry cough, fever, or chest pain. Initial clinical assessment suggested a lung tumor. Pathological evaluation was carried out on lung biopsy, wedge resection, lobectomy, or pneumonectomy specimens. All the cases showed diagnostic Reed Sternberg cells within the proper background. Immunopositivity for CD15 and CD30 was documented as well. Nodular sclerosing and mixed cellularity were the documented subtypes. Additional histologic features were a pronounced nodular growth pattern with or without necrosis, a diffuse hypersensitivity pneumonia-like picture, or acute pneumonia-like changes. Our study confirms that the recognition of Hodgkin lymphoma in lung, although based on well-established morphologic criteria, may represent a source of interpretative problems because of the unusual clinical presentation as well as the peculiar histologic changes induced within the pulmonary microenvironment.

Current concepts in the classification of interstitial lung disease

The diagnosis and classification of idiopathic interstitial pneumonias continue to be problematic areas for pathologists. The recently proposed American Thoracic Society/European Respiratory Society International Multidisciplinary Consensus Classification of the Idiopathic Interstitial Pneumonias defines specific clinical, radiologic, and pathologic criteria for each of the pulmonary disorders that encompass the idiopathic interstitial pneumonias. In this review, the highlights of this classification are presented, along with recommended guidelines for handling lung biopsy specimens and diagnosing interstitial lung diseases.