The session will provide an overview of cavitary and cystic diseases of the lung. Diagnostic criteria for cavitary lesions and cysts will be explained and the differential diagnosis will be explored in a variety of clinical situations. The pathogenesis of different forms of cavitary and cystic lesions will be explained. Key CT features will be reviewed. Attendees will learn a practical and logical approach for CT interpretation based on clinical setting, of value in everyday work.
1. To review the diagnostic criteria and differentials of cavitary lung lesions.
2. To learn about the most common causes.
3. To learn about an algorithmic approach to narrow the differential diagnosis.
A cavity is defined as “a gas-filled space, seen as a lucency or low-attenuation area, within pulmonary consolidation, a mass, or a nodule”. The wall thickness may vary considerably. There is a continuous transition from cavities to cysts. Cysts are usually thin walled (i.e., < 2 mm). A wall thickness < 7 mm is highly specific for benign disease, a thickness >24 mm is highly specific for malignant disease. However, this is not absolute, as thin-walled carcinomas do exist. An additional indicator for malignancy is the lack of perilesional centrilobular nodules around a cavity. The cavity content is unhelpful in differentiating benign and malignant lesions. Wall rim enhancement on contrast-enhanced CT is common in abscesses. A connecting pulmonary artery may be seen in smaller metastases, but not in larger ones, as the larger nodules tend to compress the vessels, so no feeding artery does not always imply benign nodules. The acute onset of symptoms is sometimes helpful to distinguish malignant and non-malignant disease. Hemoptysis is not a useful symptom to differentiate between benign and malignant cavities. Benign diseases may also cause fatigue and weight loss similar to malignancies. Acute onset of fever is usually helpful to distinguish benign disorders from malignant, but a pulmonary cancer may cause a super-infection secondary to the tumor. However, the combination of symptoms, laboratory results, past clinical history, and imaging findings leads to recognition of the correct diagnosis. This presentation will guide you through the most commonly encountered cavitary lung in adults.
1. To understand the pathophysiology of LCH.
2. To review key features on CT.
3. To learn about the various stages of the disease.
This presentation will review the characteristic and atypical CT appearances of Langerhans. The challenges in establishing a confirmed diagnosis in atypical cases will be reviewed as well as a discussion of the differential diagnoses when faced with cystic lung disease. The role of CT beyond diagnosis will be highlighted, including a review of complications and outcomes of the disease.
1. To learn about the current concepts on pathogenesis.
2. To review the typical and atypical CT features.
3. To learn about the tuberous sclerosis complex.
Lymphangioleiomyomatosis (LAM) is a rare cystic lung disease caused by infiltration of the lung with smooth muscle cells. It occurs in patients with tuberous sclerosis complex (TSC-LAM) and in a “sporadic” form in patients without tuberous sclerosis (S-LAM). S-LAM is seen exclusively in women of reproductive age while TSC-LAM may also be seen in men. Parenchymal lesions in LAM mainly include cysts, which are thin-walled, well-defined, rounded, usually small in size up to 2 cm and may reach large numbers. They have no zonal lung predominance. Nodules are extremely rare in S-LAM and are more commonly seen in TSC-LAM. They may either be solid or ground-glass and usually tiny. They represent multifocal micronodular pneumocyte hyperplasia. Pleural manifestations include chylothorax and pneumothorax. Chylous pericardial effusions may be seen. Recent guidelines for the diagnosis of LAM from the European Respiratory Society LAM task force classify LAM as definite, probable and possible. LAM is differentiated by other cystic lung diseases such as Langerhans histiocytocis (PLCH), Birt-Hogg-Dube (BHD), lymphocytic interstitial pneumonia (LIP) and amyloidosis. In PLCH the cysts have a bizarre shape, are variable in number and are upper and middle lobe predominant. In LIP the cysts are round and variable in size but usually small and random in distribution surrounded by ground glass opacity. In BHD the cysts are elliptical in shape and have a subpleural, lower zone predominance adjacent to vessels. In amyloid the cysts are variable in size but usually large and diffusely distributed. Nodules are seen in PLCH and amyloid.