Lymphadenopathy is a common radiological finding in many thoracic diseases and may be caused by a variety of infectious, inflammatory, and neoplastic conditions. This review aims to describe the patterns of mediastinal and hilar lymphadenopathy found in benign diseases in immunocompetent patients. Computed tomography is the method of choice for the evaluation of lymphadenopathy, as it is able to demonstrate increased size of individual nodes, abnormalities of the interface between the mediastinum and lung, invasion of surrounding fat, coalescence of adjacent nodes, obliteration of the mediastinal fat, and hypo- and hyperdensity in lymph nodes. Intravenous contrast enhancement may be needed to help distinguish nodes from vessels. The most frequent infections resulting in this finding are tuberculosis and fungal disease (particularly histoplasmosis and coccidioidomycosis). Sarcoidosis is a relatively frequent cause of lymphadenopathy in young adults, and can be distinguished from other diseases - especially when enlarged lymph nodes are found to be multiple and symmetrical. Other conditions discussed in this review are silicosis, drug reactions, amyloidosis, heart failure, Castleman's disease, viral infections, and chronic obstructive pulmonary disease.

Amyloidosis is a constellation of disease entities characterized by abnormal extracellular deposition and accumulation of protein and protein derivatives, which show apple-green birefringence when stained with Congo red and viewed under polarized light. Amyloid can infiltrate virtually all organ systems and can display multiple and diverse imaging findings. Pathologically, respiratory involvement occurs in 50 % of patients with amyloidosis, and its clinical signs and symptoms vary depending on whether the disease is systemic or localized. The four main patterns of respiratory tract involvement are tracheobronchial, nodular parenchymal, diffuse alveolar septal, and lymphatic. Imaging findings of amyloidosis are nonspecific and vary in each pattern; knowledge about the disease impairment type is thus very important, and amyloidosis should be considered in the differential diagnosis of other very common diseases, such as infectious diseases, neoplasms, and vasculitis. This literature review describes the main clinical and imaging manifestations of amyloidosis, focusing on respiratory tract involvement and differential diagnosis.

ObjectiveThe aim of this study was to evaluate the high-resolution computed tomography (HRCT) findings in patients diagnosed with metastatic pulmonary calcification (MPC).Materials and MethodsWe retrospectively reviewed the HRCT findings from 23 cases of MPC [14 men, 9 women; mean age, 54.3 (range, 26-89) years]. The patients were examined between 2000 and 2014 in nine tertiary hospitals in Brazil, Chile, and Canada. Diagnoses were established by histopathologic study in 18 patients and clinical-radiological correlation in 5 patients. Two chest radiologists analyzed the images and reached decisions by consensus.ResultsThe predominant HRCT findings were centrilobular ground-glass nodules (n = 14; 60.9%), consolidation with high attenuation (n = 10; 43.5%), small dense nodules (n = 9; 39.1%), peripheral reticular opacities associated with small calcified nodules (n = 5; 21.7%), and ground-glass opacities without centrilobular ground-glass nodular opacity (n = 5; 21.7%). Vascular calcification within the chest wall was found in four cases and pleural effusion was observed in five cases. The abnormalities were bilateral in 21 cases.ConclusionMPC manifested with three main patterns on HRCT, most commonly centrilobular ground-glass nodules, often containing calcifications, followed by dense consolidation and small solid nodules, most of which were calcified. We also described another pattern of peripheral reticular opacities associated with small calcified nodules. These findings should suggest the diagnosis of MPC in the setting of hypercalcemia.

Dengue fever is an arboviral disease transmitted to humans through the bites of infected female Aedes mosquitoes. Dengue virus is a member of the Flaviviridae family, and human infection can be caused by any of the four antigenically distinct serotypes (DENV 1-4). The infection has become recognized as the most important and prevalent arboviral disease in humans, endemic in almost 100 countries worldwide. Nearly 3 billion people live in areas with transmission risk. Autochthonous transmission of the virus in previously disease-free areas, increased incidence in endemic areas, and epidemic resurgence in controlled regions could increase the risk of contracting more severe forms of the disease, such as dengue hemorrhagic fever (DHF)/dengue shock syndrome (DSS). Symptomatic dengue virus infection can present with a wide range of clinical manifestations, from mild fever to life-threatening DSS. Thoracic complications may manifest as pleural effusion, pneumonitis, non-cardiogenic pulmonary edema, and hemorrhage/hemoptysis. No vaccine is currently available and no specific treatment for dengue fever exists, but prevention and prompt management of complications in patients with DHF can help reduce mortality. This review describes the main clinical, pathological, and imaging findings of thoracic involvement in DHF.

Pulmonary fungal infections, which can be opportunistic or endemic, lead to considerable morbidity and mortality. Such infections have multiple clinical presentations and imaging patterns, overlapping with those of various other diseases, complicating the diagnostic approach. Given the immensity of Brazil, knowledge of the epidemiological context of pulmonary fungal infections in the various regions of the country is paramount when considering their differential diagnoses. In addition, defining the patient immunological status will facilitate the identification of opportunistic infections, such as those occurring in patients with AIDS or febrile neutropenia. Histoplasmosis, coccidioidomycosis, and paracoccidioidomycosis usually affect immunocompetent patients, whereas aspergillosis, candidiasis, cryptococcosis, and pneumocystosis tend to affect those who are immunocompromised. Ground-glass opacities, nodules, consolidations, a miliary pattern, cavitary lesions, the halo sign/reversed halo sign, and bronchiectasis are typical imaging patterns in the lungs and will be described individually, as will less common lesions such as pleural effusion, mediastinal lesions, pleural effusion, and chest wall involvement. Interpreting such tomographic patterns/signs on computed tomography scans together with the patient immunological status and epidemiological context can facilitate the differential diagnosis by narrowing the options.