Abstract Interstitial lung diseases (ILD) are a heterogeneous group of diseases and one of the differential diagnosis which have to be excluded during diagnostic procedures are malignancies. We will present four patients who were referred to our Department because of suspicion of interstitial lung diseases according to radiology find- ing. In one case only, one of the radiologist’s differential diagnosis was pulmonary lymphangitic carcinomatosis. All four patients had exertional dyspnea and dry cough which are nonspecific and can be first manifestation of ILD or obstructive lung diseases. After diag- nostic evaluation in three cases, diagnosis was pulmonary lymphan- gitic carcinomatosis due to metastatic lung adenocarcinoma and in one due to metastatic adenocarcinoma of unknown primary origin. Patients with lymphangitic carcinomatosis have poor prognosis without treatment and usually die because of respiratory failure. With these four cases we want to highlight importance of thinking about malignancies when we have patients with suspicion of inter- stitial lung disease especially when reticular pattern is present on chest X ray. We also wanted to show how important is radiology finding and multidisciplinary approach, and how radiologist’s dif- ferential diagnosis can be very helpful in making decisions in fur- ther investigations and way of clinicians thinking. Introduction Interstitial lung diseases (ILD) are a heterogeneous group of disorders and one of the differential diagnosis that we have to exclude is neoplastic process. Lung metastases are present in 30- 40% of patients with malignant disease and 6-8% of this group of patients have pulmonary lymphangitic carcinomatosis (PLC) [1]. Almost any cancer has the ability to spread to the lungs and pri- mary tumors most commonly associated with PLC are breast, stomach, lungs, pancreas and prostate [1,2]. PLC represents one of the differential diagnosis of interstitial lung abnormalities. One of the most common finding of PLC on high resolution computed tomography (HRCT) is nodular thickening of the peribronchovas- cular interstitium, apart from the interlobular septal thickening [3]. We will present four patients who were admitted to our Department because of radiology finding of interstitial lung changes and presumed diagnosis of ILD. After diagnostic proce- dures, in three cases the final diagnosis was lung cancer with PLC, and in the fourth case diagnosis was PLC from an adenocarcinoma of unknown primary origin. Cases Reports Case #1 A 61-year-old non-smoker female was admitted to our Department because of progressive dyspnea and respiratory fail- ure. She had systemic arterial hypertension in her medical history and otherwise she was healthy. She started to notice progressive dyspnea four months before admission and reported cough of 1- month duration. She did not have fever and chest pain but she lost 8 kg in the last 3 months. She also had back pain during last 4 months and she was referred to neurologist in another hospital. MR of thoracic and lumbar spine was done which shoved bone lesions suspected of metastatic bone lesions so further investiga- tion was suggested. Pulmonary auscultation revealed bilateral, dif- Correspondence: Ana Hecimovic, Department for Lung Diseases, University Hospital Centre, Jordanovac 104, 10000 Zagreb, Croatia. Tel.+385.1.2385231 - Fax: +385.1.2385388. E-mail: anahecimovic1978@gmail.com Key words: Interstitial lung disease; neoplasm metastasis; lung neo- plasms; lymphatic metastasis. Contributions: AH, MJ, MS, conception and design of the study, manu- script drafting, critical revision; AVD, FD, data collection, critical revi- sion of the article. All the authors read and approved the final version of the article. Conflict of Interest: A. Hecimovic reported personal fees from Roche, Boehringer Ingelheim and MSD outside the submitted work. M. Jakopovic and M. Samarzija reported personal fees from Roche, Boehringer Ingelheim, Novartis, Astra Zeneca and Bristol-Mayers, out- side the submitted work. A. Vukic Dugac reported personal fees from Astra Zeneca, Novartis, Boehringer Ingelheim and Teva, outside the submitted work. F. Dzubur reported personal fees from MSD outside the submitted work. Funding: This research did not receive any specific grant from funding agencies in the public, commercial or not-of-profit sectors. Received for publication: 27 January 2019. Accepted for publication: 14 May 2019. ©Copyright A. Hecimovic et al., 2019 Licensee PAGEPress, Italy Monaldi Archives for Chest Disease 2019; 89:1041 doi: 10.4081/monaldi.2019.1041 This article is distributed under the terms of the Creative Commons Attribution Noncommercial License (by-nc 4.0) which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited. [Monaldi Archives for Chest Disease 2019; 89:1041] [page 13] Monaldi Archives for Chest Disease 2019; volume 89:1041 Metastatic cancer mimics interstitial lung disease. Cases when we need fast diagnosis and treatment Ana Hecimovic 1 , Marko Jakopovic 1,2 , Andrea Vukic Dugac 1,2 , Feda Dzubur 1,2 , Miroslav Samarzija 1,2 1 Department for Lung Diseases, University Hospital Centre Zagreb; 2 School of Medicine, University of Zagreb, Croatia Non-commercial use only