available, three patients with LIP, three with malignant lymphoma, and one with pseudolymphoma were described [4]. The natural history of LIP is variable, ranging from a benign course (stabilization or improvement) to the evolution of BALT lymphoma [10, 44].

14.3.7Cryptogenic Organizing Pneumonia

COP is a pathological subtype of ILD characterized by intra-alveolar buds of connective tissue. Typical radiologic findings include bilateral patchy alveolar opacities with air-bronchograms and normal lung volumes [45]. While COP has been described previously in the setting of several autoimmune disorders – mainly rheumatoid arthritis – it occurs quite rarely in pSS [45]. Since the clinical and radiological features of COP are reminiscent of those of community acquired pneumonia, diagnosis is often delayed, usually after one or more failed courses of antibiotics [46, 47].

14.3.8Clinical Features

Patients with pSS and ILD typically present with dyspnea and cough [36]. On physical examination, bibasilar crackles are often present. However, the absence of symptoms does not preclude subclinical respiratory involvement, which is detected most effectively by HRCT and pulmonary function tests [11, 19].

14.3.9Imaging Studies

HRCT is more sensitive in detecting parenchymal lung abnormalities than is chest radiography and provides important information regarding the pattern of pulmonary involvement [18, 23, 48]. Franquet et al. reported HRCT abnormalities in 34% of patients with pSS compared to 14% of those who underwent plain radiographs [18]. Similar findings were described by Uffmann et al., who reported abnormal HRCT findings in more than 60% of asymptomatic pSS patients with normal radiographs [19].

The most common findings on chest radiographs in pSS patients with ILD are linear, reticular, and reticulonodular opacities, predominantly seen in the lower lung zones [3, 37, 49]. Bullae and pleural abnormalities are detected occasionally. HRCT patterns suggestive of ILD include ground-glass attenuation [13, 16, 18], subpleural small nodules, non-septal linear opacities, interlobular septal thickening, and honeycombing in subpleural areas [16, 19, 49] (Table 14.3). In the series of Franquet et al., honeycombing was detected in 8% of patients, always in as bilateral, asymmetric, peripheral lower lung distribution [18]. The corresponding figure in the study by Uffmann et al. was 24% [19]. In the study of Papiris et al., interstitial