A 59-year old man was admitted to the chest department with a one-week history of dry cough and acute onset of fever and dyspnea. Besides interstitial thickening related to undifferentiated glycogen positive mesenchymal cells all tissue samples showed growth abnormalities with reduced alveolarization. Pulmonary Langerhans cell histiocytosis. The differential diagnosis is the same as the list above. Centrilobular emphysema: low attenuation areas without walls. The most common cause of a septal pattern as the predominant or only pattern is hydrostatic pulmonary edema ( Figs. A structured approach to interpretation of HRCT involves the following questions: These morphologic findings have to be combined with the history of the patient and important clinical findings. On the left another patient with ground glass pattern in a mosaic distribution. There is uniform destruction of the underlying architecture of the secondary pulmonary lobules, leading to widespread areas of abnormally low attenuation. In severe panlobular emphysema, the characteristic appearance of extensive lung destruction and the associated paucity of vascular markings are easily distinguishable from normal lung parenchyma. Smooth septal thickening is usually seen in interstitial pulmonary edema (Kerley B lines on chest film); lymphangitic spread of carcinoma or lymphoma and alveolar proteinosis. InterstIal lung dIseases Dr. Shrikant Nagare 2. When thickened, interlobular septa (septal lines) are seen on the radiograph as short (1–2 cm) lines perpendicular to and continuous with the pleura (Kerley B lines) or as longer (2–6 cm) lines oriented toward the hila (Kerley A lines) ( Fig. Interstitial marking: This is frequently a non specific finding on radiographic evaluation of the lungs can be exaggerated by infection, fluid in lungs of cardiac or other origin and scarring from previous infection. Most patients who are evaluated with HRCT, will have chronic consolidation, which limits the differential diagnosis. Notice the pneumothorax. AJR 2010 Interstitial Lung Diseases: A pattern-based approach pulm. It was a patient with low-grade fever, progressive shortness of breath and an abnormal chest radiograph. Although septal thickening may be seen in sarcoidosis, it is seldom the main finding. Idiopathic pulmonary fibrosis (IPF), accounts for more than 60% of the cases of UIP. This suggested a chronic disease. Centrilobular distribution The lower zone predominance is demonstrated when you scroll through the images. The clue here is the enlargement of pulmonary arteries (arrow) in the areas of ground glass. Radiographics. 5.17 ; see also Fig. Cystic spaces are seen in approximately 30% of patients with Pneumocystis jirovecii pneumonia. Mild subpleural reticulation is seen in the right upper lobe, Nonspecific interstitial pneumonia: relative subpleural sparing. In patients with a perilymphatic distribution, nodules are seen in relation to pleural surfaces, interlobular septa and the peribronchovascular interstitium. Nonspecific interstitial pneumonia. Broncho-alveolar cell carcinoma (BAC) may present as: Treatable or not treatable? In both ground glass and consolidation the increase in lung density is the result of replacement of air in the alveoli by fluid, cells or fibrosis. UIP with lung fibrosis is also a common pattern of auto-immune disease and drug-related lung injury. This finding is helpful in distinguishing PLC from other causes of interlobular septal thickening like Sarcoidosis or cardiogenic pulmonary edema. Proliferation of these cells along the bronchioles leads to air trapping and the development of thin-walled lung cysts. 33. On the left a case with multiple round and bizarre shaped cysts. (A) Posteroanterior chest radiograph shows reticulation in the left middle and lower lung zones and, to a lesser extent, right middle lung zone, Pulmonary fibrosis in sarcoidosis. Sarcoidosis end-stage: consolidation as a result of massive fibrosis perihilar and in upper lobes. Is it pus, edema, blood or tumor cells (Table on the left). Although thickening of the interlobular septa is relatively common in patients with interstitial lung disease, it is uncommon as a predominant finding and has a limited differential diagnosis (Table). Pulmonary Langerhans cell histiocytosis is a disease characterized histologically by infiltration of the lung by Langerhans cells that typically manifests in young adults and is seen almost exclusively in smokers. (Courtesy Dr. Julia Flint, Department of Pathology, Vancouver General Hospital, Vancouver, Canada. Answered on Mar 31, 2018. They also occur in silicosis, coal-worker's pneumoconiosis and lymphangitic spread of carcinoma. This finding can allow honeycombing to be distinguished from paraseptal emphysema in which subpleural cysts usually occur in a single layer. Conglomeration of cysts in the left upper lobe has led to the formation of large cysts with bizarre shapes. The secondary lobule is the basic anatomic unit of pulmonary structure and function. Perilymphatic distribution NSIP is characterized by the diffuse thickening of the alveolar wall with fibrosis, which is associated with preservation of the architecture of the alveoli. This case is one of the possible patterns of nonspecific interstitial pneumonia (NSIP). It represents dilated and impacted (mucus or pus-filled) centrilobular bronchioles. Thickening of the interlobular septa may be caused by edema, cellular infiltration, or fibrosis. Langerhans cell histiocytosis: early nodular stage before the typical cysts appear. Lymphangiomyomatosis (LAM): regular cysts in woman of child-bearing age. Thickening of the lung interstitium by fluid, fibrous tissue, or infiltration by cells results in a pattern of reticular opacities due to thickening of the interlobular septa. Hypersensitivity pneumonitis: ill defined centrilobular nodules. The images show two cases with GGO, one without fibrosis and potentially treatable and the other with traction bronchiectasis indicating fibrosis. Drawing of the right lung illustrates reticular pattern. 5.18 ). edema lymphang. Reticular pattern on high-resolution CT in idiopathic pulmonary fibrosis. 5.23 ). In this article a practical approach is given for the interpretation of HRCT examinations. The characteristic high-resolution CT finding consists of numerous thin-walled, air-filled cysts surrounded by normal lung parenchyma (see Fig. The CT findings of RB-ILD include ground-glass opacities, centrilobular nodules, and interstitial thickening with upper-lung-zone predominance [6, 7]. Single or multiple cysts typically superimposed on ground-glass opacities also are seen in approximately 60% of patients with lymphoid interstitial pneumonia and 13% of patients with subacute hypersensitivity pneumonitis.