A 41-year-old man working as a chauffeur was presented to his GP with subsequent back pain after rotator cuff injury. Physical examination was unremarkable. In terms of medical history there was no exposure to tuberculosis, he had a 20 pack year history of smoking and there was no relevant surgical history. Although his chest X-ray was normal, the back pain insisted. A MRI of the chest was performed revealing a right paravertebral mass (Fig. 1b). In order to better define the lesion and exclude any other organ involvement, a computed tomography (CT) of thorax and abdomen (with contrast) was performed. The CT confirmed a 3 cm right lower lobe paravertebral soft tissue density mass lesion, invading into the adjacent pleural surface (Fig. 1a). Lymphadenopathy of station 2R and station 4R was noted. An extension across the T5 and T6 vertebral levels with frank destruction of the right T6 costovertebral joint and some enlargement of the right neural foramina were also found. Lungs, pleural spaces, mediastinum, thoracic esophagus and abdomen structures were of normal appearance. In order to specify the histopathology of the lesion, a CT guided biopsy was performed but it was not diagnostic. After multidisciplinary meeting and after written consent was obtained from the patient a right 3 ports VATS biopsy of the mediastinal mass was performed. The postoperative course was unremarkable and the patient was discharged in stable condition on the 3rd postoperative day. With regard to the treatment plan, the patient received initially 60mg of enteric-coated corticosteroids (Prednisolone) that have been gradually tapered after 4 weeks due to patient's steroid-related psychosis. These were replaced with rituximab at a 1 g IV dose every 15 days for a total of two doses. The PET/CT scan performed 3 months later showed that the paravertebral lesion was resolved, with only minimal activity. The visualized part of the musculoskeletal system including the spine showed physiological distribution of fluorodeoxyglucose (FDG). There were no FDG avid lymphadenopathy or other organ involvement.
Subsequent histological examination of the specimen was performed. The macroscopic description of the lesion was characterized by multiple fragments of firm dark brown and cream colored nodular tissue measuring 15 x 15 x 3 mm aggregate. It was firmly adhered to the lung and was highly vascularized. With reference to the microscopic description, sections of lung parenchyma and adjacent fibrous tissue showed a dense lymphoplasmacytic infiltration predominantly located in the lung parenchyma (Fig. 2a, b, c). The fibrotic areas adjacent to the lung parenchyma showed a similar but less pronounced lymphoplasmacytic inflammatory infiltration. Within the lung parenchyma there were foci suggested but not diagnostic for obliterative phlebitis (Fig. 2d). The alveolar spaces showed occasional pneumocyte metaplasia with no cytological atypia. Immunohistochemistry performed showed (Fig. 3) that the inflammatory infiltration was predominantly composed of CD138 (Fig. 3a) positive plasma cells along with moderate amount of CD3 positive T-lymphocytes and scattered CD20 positive B-lymphocytes (Fig. 3d). Most plasma cells were noted to express IgG (Fig. 3b) and a large proportion of these plasma cells are also noted to co-express IgG4 (Fig. 3c). The IgG4 positive plasma cells, in areas were noted to amount up to more than 150 cells per high power field and amount up to more than 40% of the total plasma cells present. CK7 and TTF-1 highlight the pulmonary parenchymal architecture which was in areas distorted due to marked inflammatory component (Fig. 3f and g). Serum IgG4 levels were also elevated (3,95 g/l) with overall IgG within range of normality. A diagnosis of IgG4-related lung disease was made considering the lymphoplasmacytic inflammatory infiltrate of the lesion, the laboratory findings and the radiological image.
CT scan with contrast revealed a 3 cm right lower lobe paravertebral lesion extending across the T5, and ,T6 vertebral levels, and.