CT Findings of Thoracic Paravertebral Lesions in IgG4-Related Disease.

OBJECTIVE. The objective of our study was to characterize the CT findings of IgG4-related paravertebral lesions. MATERIALS AND METHODS. We selected cases of IgG4-related paravertebral lesions that satisfied two inclusion criteria: first, lesions in patients with IgG4-related disease diagnosed by a multidisciplinary approach between April 2007 and June 2018; and, second, patients who had soft-tissue lesions in paravertebral regions on CT images. We added one case of an IgG4-related paravertebral lesion diagnosed pathologically in 2003. Finally, the study consisted of 30 patients (25 men and five women; median age, 69.5 years). We retrospectively evaluated the CT findings of the paravertebral lesions. RESULTS. A total of 31 paravertebral lesions were identified in 30 patients. All lesions were located around thoracic vertebrae, particularly the lower thoracic regions (n = 30). Twenty-six lesions (84%) involved two or more vertebrae in a row. The right side of vertebrae was predominantly affected in all cases except one (30/31 lesions). Radiologically, the paravertebral lesions were characterized as a bandlike, demarcated soft-tissue mass (mean maximum thickness, 8.7 mm) with homogeneous enhancement on late phase images of contrast-enhanced CT. All patients had IgG4-related lesions at other sites. Histologically, paravertebral lesions showed sclerosing inflammation consisting of diffuse lymphoplasmacytic infiltrations with many IgG4-positive plasma cells and irregular fibrosis. CONCLUSION. IgG4-related paravertebral lesions occur mainly in the right side of the lower thoracic vertebrae and present as a homogeneously enhanced bandlike mass corresponding to plasma cell-rich sclerosing inflammation.