Image Findings Can Predict Possible Immunoglobulin G4-Related Diseases: A Case Report.

A 66-year-old man with a history of well-differentiated rectal adenocarcinoma surgery 10 years before had been followed up for his abdominal mass, 1.2 cm in size, just adjacent to the inferior vena cava. The retroperitoneal mass fortunately showed only a nominal growth for more than five years. The retroperitoneal mass, however, showed rapid growth up to 2.2 cm after the squamous lung cancer operation. Ultrasound showed that the mass had internal punctate high echoes and enhanced posterior echoes. Magnetic resonance imaging (MRI) showed low signals on T1-weighted images, low signals with intermingling of faint high signals on T2-weighted images, and mixed high and low signals on diffusion-weighted images (DWIs). Positron emission tomography showed a maximum standardized uptake value of 2.7. These findings led us to judge that the mass was not a possible malignancy. However, the patient's strong preference for surgical removal of the mass made us treat it by surgical intervention. Postoperative pathological study showed that the lymphatic tissue was surrounded by a thick fibrous capsule and also had a large amount of fibrous components within the lymph node. In addition to the obliterative phlebitis within the fibrous components, numerous IgG4-positive plasma cells on immunostaining led to the diagnosis of IgG4-related disease. The patient recovered uneventfully and has been well without any recurrence for more than four years. Diagnostic physicians should note that IgG4-related disease can have very weak enhancement on CT, low signals both on T2-weighted images and DWIs, and internal punctate high echoes presumably due to the abundant presence of micro-voids in its fibrous components.