Isolated middle mediastinal mass associated with immunoglobulin G4-related disease

Abstract

Background: Immunoglobulin G4-related disease (IgG4-RD) is a multi-organ disorder predominantly occurring in middle-aged to elderly male patients characterized by multi-organ fibrosis, specific pathological findings of storiform fibrosis with IgG4-positive plasma cell infiltration, and elevated serum IgG4 level. We herein report a rare presentation of IgG4-RD forming an isolated mass in the middle mediastinum mimicking a mediastinal tumor and discuss the clinical significance of mediastinal IgG4-RD.

Case presentation: An 82-year-old male patient without any symptom was referred due to left middle mediastinal mass (3.8 × 2.4 cm). Because of suspected lymphoma, Castleman's disease, and lymphangitis due to tuberculosis, we performed a thoracoscopic resection for diagnosis and treatment. The mass was yellowish white with well-encapsulated, and storiform fibrosis with plasma cell infiltration, and obliterative phlebitis were observed microscopically. Additional immunohistochemical stain revealed IgG4-RD. Other radiological findings and serological results did not show evidence of other organs being affected from IgG4-RD nor autoimmune diseases. He is now followed at outpatient clinic without additional treatment for over a year, and an enhanced computed tomography does not show any recurrence.

Conclusion: It was a rare presentation of IgG4-RD forming isolated middle mediastinal mass, which suggests that we might suspect IgG4-RD for undetermined mediastinal mass in case of middle to elderly male patient.

Keywords: Immunoglobulin G4-related disease; mediastinal tumor; Systemic autoimmune disease.

Fig. 1

Preoperative imaging. a Chest X-ray showed an abnormal mass in the left mediastinum (yellow arrowheads). b Enhanced computed tomography of lung field (yellow arrowheads). c Enhanced computed tomography of mediastinal field; the left mediastinal mass was a homogenous round-shaped 3.8 × 2.4 cm in diameter (yellow arrowheads)

Fig. 2

Intraoperative view of the left-side mediastinum and macroscopic findings of the mediastinal mass. a Intraoperative view showed that the mass was well-encapsulated neighboring to the aorta (yellow arrowheads). b Cross section of the mediastinal mass was elastic and homogenous yellowish; white bar = 1 cm

Fig. 3

Pathological findings of the mediastinal mass. a Hematoxylin and eosin stain showed a fibrosis with plasma cell infiltration (× 40). b Immunohistochemical stain of IgG showed that IgG plasma cell infiltration was confirmed (× 200). c Immunohistochemical stain of IgG4 showed that IgG4-positive plasma cells were ascertained and the IgG4/IgG cell ratio was ≥ 40% (× 200). d Elastica van Gieson stain showed that an obliterative phlebitis was detected (× 200). IgG Immunoglobulin G

Fig. 4

Image of F-18–2-fluoro-2-deoxy-D-glucose positron emission tomography computed tomography. No other affected organs were detected in the whole-body imaging postoperatively