The most common histological pattern of lung fibrosis in SSc is nonspecific interstitial pneumonia (NSIP), which might be mild (part a) or extensive (part b); NSIP is characterized by relative preservation of lung architecture and often a homogeneous ‘ground glass’ change within the lungs on CT imaging (GG arrow). NSIP might have cellular or fibrotic subtypes. By contrast, compared with NSIP, the less common usual interstitial pneumonia (UIP) pattern of fibrosis (part c) has a much more altered architecture, a more variable severity of fibrotic lesions and a less homogeneous pattern with dense fibrosis and cystic changes, termed honeycombing (HC arrow). Pulmonary hypertension (part d) is characterized by enlargement of the pulmonary artery on CT imaging (PA arrow). A designation of pulmonary arterial hypertension (PAH) can be made if only mild lung fibrosis is present, as otherwise a classification of group III pulmonary hypertension is made. It is also important to note whether CT features of pulmonary veno-occlusive disease are present, such as septal lines, nodules or lymphadenopathy (not shown).