|ECR 2019 / C-2418|
|HRCT features in patients with undifferentiated connective tissue disease|
Aims and objectives
Lung involvement is common in connective tissue diseases (CTDs), an heterogeneous group of systemic immunologically mediated inflammatory disorders. 
As many as 25% of patients with features of a systemic autoimmune disease do not fulfill American College of Rheumatology (ACR) classification criteria for a defined CTD, such as Systemic Sclerosis, Systemic Lupus Erythematosus, Sjogren’s Syndrome, Polymyositis/Dermatomyositis and Rheumatoid Arthritis. These patients are considered to have undifferentiated connective tissue disease (UCTD). 
The natural history of UCTD still remains unknown and unpredictable. Most of cases (65-94%) do not develop a defined CTD (stable UCTD) and are usually mild, whereas some patients can evolve over time into a specific CTD, usually within 5 years. 
UCTD clinical manifestations are nonspecific, including arthritis/arthralgia, Raynaud’s phenomenon, skin rash and mild cytopenias. Major organ involvement is occasionally observed, but interstitial lung disease (ILD) has been frequently reported, often determining increased mortality and morbidity in this group of patients. 
ILD is a various group of disorders that diffusely affect the pulmonary parenchyma with inflammation and/or fibrosis; it results from variable etiologies but share common radiologic, pathologic and clinical manifestations.
To date, only few studies have investigated thoracic manifestations associated with UCTD, particularly the lung CT pattern of ILD, and significantly controversies exist; thus the interpretation of thoracic images obtained in these patients can be challenging.
High-resolution computed tomography (HRCT) is the imaging technique of choice for evaluation of the presence and extent of pulmonary parenchymal involvement, with greater sensitivity than conventional chest radiography.
The purpose of our study was to evaluate computed tomographic (CT) thoracic findings of undifferentiated connective tissue disease (UCTD) and identify the most common CT patterns of lung involvement in this condition.
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