Introduction. Cystic lung diseases are rare (orphan) diseases. Lung cysts are an important X-ray and morphological sign that contributes to the correct diagnosis. The aim of the researchwas to describe histologic features and computed tomography findings in patients with pulmonary Langerhans cell histiocytosis (PLCH), lymphangioleiomyomatosis (LAM), primary malignant lung tumors, and endometriosis of the lung. Materials and methods. We evaluated video-assisted surgical lung biopsies from 139 patients, with 86 patients having LAM, 47 having PLCH, and in threes having primary peripheral lung adenocarcinoma and endometriosis of the lung. The average age of patients with LAM was 41±10 years, LCG – 32±11 years, lung adenocarcinoma – 62±3.5 years, and endometriosis of the lung – 32±4.1 years. All patients had undergone high-resolution computed tomography of the lungs (HRCT) before the biopsy was obtained. We performed histological and immunohistochemical examinations of lung tissue specimens. Antibodies to CD1a, SMA, HMB-45, CD207 (langerin), CD10, receptors to progesterone, and estrogen were used in the study. Results. We described HRCT, histological, and immunohistochemical features of cystic lung diseases, including characteristics of the walls of cystic cavities in patients with PLCH, LAM, primary malignant lung tumors, and endometriosis of the lung. Conclusion. The variety of causes of lung cysts required a differential diagnosis, considering the patients’ ages, HRCT data indicating the localization of the pathological process, histology, and immunohistochemistry if necessary. Keywords: сystic lung diseases, computed tomography, pathological anatomy, Langerhans cell histiocytosis, lymphangioleiomyomatosis, malignant tumors, endometriosis

Smoking-related interstitial fibrosis (SRIF) is a recently described disease which is common finding in a long-term cigarette smokers.Aim. To acquaint readers with relatively unknown interstitial disease. We describe a case of a smoking patient with a long smoking history and squamous cell carcinomas of the larynx and lung who complained of an unproductive cough, sore throat, hoarseness, difficulty in nasal breathing, and shortness of breath during exercise. Obstructive disorders, lung hyperinflation, and a severe decrease in diffusion capacity reflected the signs of severe emphysema in combination with fibrotic changes found by high resolution computed tomography (CT). X-ray picture and characteristic histological changes made it possible to diagnose SRIF.Conclusion. Diagnostics of the disease should be based on CT-signs, histologic picture and functional data. The prognosis is relatively favorable.