Niemann-Pick disease is a rare autosomal recessive lysosomal storage disease with three subtypes. Types A and B result from a deficiency of acid sphingomyelinase activity, associated with the accumulation of lipid-laden macrophages (so-called Niemann-Pick cells) in various tissues, especially the liver and spleen. Type A is a fatal neurodegenerative disorder of infancy. Type B Niemann-Pick disease is a less severe form with milder neurological involvement, characterized by hepatosplenomegaly, hyperlipidemia, and pulmonary involvement; most patients live into adulthood. Type C Niemann-Pick disease is a complex lipid storage disorder caused by defects in cholesterol trafficking, resulting in a clinical presentation dominated by neurological involvement. Pulmonary involvement occurs in all three types of Niemann-Pick disease, but most frequently in type B. Respiratory manifestations range from a lack of symptoms to respiratory failure. Progression of respiratory disease is slow, but inexorable, due to the accumulation of Niemann-Pick cells in the alveolar septa, bronchial walls, and pleura, potentially leading to a progressively worsening restrictive pattern on pulmonary function testing. Bronchoalveolar lavage has important diagnostic value because it shows the presence of characteristic Niemann-Pick cells. Radiographic findings consist of a reticular or reticulonodular pattern and, eventually, honeycombing, involving mainly the lower lung zones. The most common changes identified by high-resolution computed tomography are ground-glass opacities, mild smooth interlobular septal thickening, and intralobular lines. The aim of this review is to describe the main clinical, imaging, and pathological aspects of Niemann-Pick disease, with a focus on pulmonary involvement.

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.

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Pulmonary malakoplakia is a rare lung lesion more frequently found in immunocompromised patients than in immunocompetent individuals. In this study, we report the challenging case of a young immunocompetent patient with an irregular pulmonary nodule with peripheral cysts who, after undergoing surgery, was diagnosed with malakoplakia. Due to the rarity of the disease and the similarity of this condition to malignant neoplasms, cytopathological or histopathological examinations are necessary for the correct diagnosis. A description of pulmonary malakoplakia with peripheral cysts has not been previously published in the literature.

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A 49-year-old woman with a history of myocardial revascularization surgery presented at the emergency department of a tertiary-care hospital with the complaint of chest pain. After initial clinical, laboratory, and radiographic assessment, a 64-multidetector computed tomography (MDCT) scan was ordered to elucidate the X-ray findings of a linear opacity near the right lung base, apparently parallel to the right hemidiaphragm, and an almost vertical elongated structure on the middle third of the right lung.The abnormalities visible on the X-ray were also depicted on the CT scout image (Fig. 1). Volumetric 64-MDCT acquisition was performed in the axial plane with intravenously injected iodine contrast in association with multiple reformatting techniques such as maximum intensity projection (MIP; Fig. 2a), minimum intensity projection (MinIP), volume rendering (Fig. 2b), and virtual bronchoscopy. The examination showed a thin linear structure that coursed obliquely downward from the right thoracic wall, through the lower-lung parenchyma, and into the right diaphragmatic crus, where it displayed soft-tissue density. The vessels coursing to the basal pyramid merged together through a hiatus within that structure just before splitting into their respective segments. A single pulmonary vein drained into the left atrium; its shape and course resembled the ''scimitar'' of hypogenetic lung syndrome, although no anomalous pulmonary venous return was identified.The accessory diaphragm is a rare anomaly in which the right hemothorax is portioned into two compartments by a musculotendinous membrane resembling a diaphragm. This malformation is often associated with vascular and airway anomalies [1,2]. A gap (hiatus) in the accessory diaphragm is usually present to allow the passage of vessels and bronchi to supply this portion of lung. The radiological appearance of this lung portion depends on whether it is aerated, and it is easily mistaken for fibroatelectatic strands on X-rays or CT scans [1, 2]. Fig. 1 Computed tomography scout image showing a curvilinear opacity near the right lung base, apparently parallel to the right hemidiaphragm (arrow), and an almost vertical elongated structure in the middle third of the right lung (arrowheads)